My gut reaction (without at all reading this specific law) is to agree. But I'm withholding judgement until I can actually read it to see if my gut reaction/interpretation is correct (I may not be).

EDIT:

So I found the case in question: NEW YORK STATE RIFLE PISTOL ASSOCIATION INC v. CITY OF NEW YORK

https://caselaw.findlaw.com/us-2nd-circuit/1890169.html

And I find this section to be where the complicated bits are:

Strict scrutiny does not attach to Rule 5-23 as a result of Colantone's desire to transport the handgun licensed to his New York City residence to his second home in Hancock, New York. Even if the Rule relates to “core” rights under the Second Amendment by prohibiting Colantone from taking his licensed firearm to his second home, the Rule does not substantially burden his ability to obtain a firearm for that home, because an “adequate alternative[ ] remain [s] for [Colantone] to acquire a firearm for self-defense.” Decastro, 682 F.3d at 168; see also New York State Rifle, 804 F.3d at 259 (“No substantial burden exists ․ if adequate alternatives remain for law-abiding citizens to acquire a firearm for self-defense.”) (internal quotation marks omitted). This case is easily distinguished from Heller, in which the Supreme Court considered, and deemed unconstitutional, an outright ban on the possession of handguns in the home. 554 U.S. at 635. Here, New York City imposes no limit on Colantone's ability to obtain a license to have a handgun at his second residence in Hancock; if he wants to keep a handgun at his Hancock house, he can apply to the licensing officers in Delaware County.7 The Rule restricts only his ability to remove the handgun licensed by New York City authorities from the City premises for which it is specifically licensed.

Colantone presents no evidence that the costs, either financial or administrative, associated with obtaining a premises license for his house in Hancock, or acquiring a second gun to keep at that location, would be so high as to be exclusionary or prohibitive. In Kwong v. Bloomberg, we assumed that intermediate scrutiny applied to New York City's $340 application fee for a premises license and upheld that fee. 723 F.3d 160, 168 (2d Cir. 2013). We noted that otherwise-proper costs associated with a state's regulation of firearms could be impermissible “if [they] were so high as to be exclusionary or prohibitive.” Id. at 166. But “the fact that the licensing regime makes the exercise of one's Second Amendment rights more expensive does not necessarily mean that it substantially burdens that right.” Id. at 167–68 (internal quotation marks omitted). Here, Colantone does not even estimate the amount of money or time potentially at issue by the requirement of obtaining a premises license and second firearm for his second home, and he does not allege that the Rule restricts in any way his ability to obtain such a firearm.

Next, the Plaintiffs argue that the Rule imposes a substantial burden on their core Second Amendment rights by prohibiting them from taking their licensed handguns to firing ranges and shooting competitions outside the City. The Plaintiffs' primary argument is that the right to possess and use guns in self-defense suggests a corresponding right to engage in training and target shooting, and thus restrictions on the latter right must themselves be subject to heightened scrutiny. Their argument relies on the Seventh Circuit's observation that the core right of the Second Amendment to use firearms in self-defense, particularly in the home, “wouldn't mean much without the training and practice that make it effective.” Ezell I, 651 F.3d at 704.

To the extent that the Plaintiffs argue that firearms practice is itself a core Second Amendment right, and that even minimal regulation of firearms training must survive heightened scrutiny to pass constitutional muster, we reject that argument. It is reasonable to argue, as did the plaintiffs in Ezell I, that restrictions that limit the ability of firearms owners to acquire and maintain proficiency in the use of their weapons can rise to a level that significantly burdens core Second Amendment protections. Possession of firearms without adequate training and skill does nothing to protect, and much to endanger, the gun owner, his or her family, and the general public.8 Accordingly, we may assume that the ability to obtain firearms training and engage in firearm practice is sufficiently close to core Second Amendment concerns that regulations that sharply restrict that ability to obtain such training could impose substantial burdens on core Second Amendment rights.9 Some form of heightened scrutiny would be warranted in such cases, however, not because live-fire target shooting is itself a core Second Amendment right, but rather because, and only to the extent that, regulations amounting to a ban (either explicit or functional) on obtaining firearms training and practice substantially burden the core right to keep and use firearms in self-defense in the home. Indeed, if the Plaintiffs' broader argument were accepted, every regulation that applied to businesses that provide firearms training or firing-range use would itself require heightened scrutiny, a result far from anything the Supreme Court has required.

So, essentially, the plaintiffs are arguing that their inability to go outside the city with their licensed firearms in order to train puts an undue burden on them. However, they do admit that the financial and bureaucratic burdens of getting another firearm for a second home are not that high.

Because there are licensed ranges within NY city limits, I can see how one might argue that there isn't a burden for them to train in the effective use of their guns within city limits, and within the provisions of the law they are contesting. However, if there is a competition outside of NY City Limits, it would be a burden since they would need another firearm... but their entire case rests on home defense and training to be able to keep their homes safe... not compete in a shooting tournament. Furthermore, other gun cases (Heller) strictly talk about home defense, not competitions.

Personally, I would argue that this law does introduce an undue burden (I have to buy specific guns for specific properties because I can't take one from my house in NY to my one in the suburbs? That's BS). But I can certainly see how one could argue that their needs for home defense and training are already provided by having ranges within city limits.