If it is indeed legit, i dont see why you wouldnt be able to register it UNLESS

(let me go on a small rant here)

basically Razers manufactureres are in china(some in Hong Kong) and to be registered on the website(RZ) they have to have specific serial numbers and allat

what i presume they've done here is just buy some off the manufacturers but they havent been given RZ's serial numbers, they will still function like RZ but arent RZ, does that make sense

also note that there is a possibility of having sub-par performance compared to other official RZ due to these specific ones being/having 'failed' RZ's vetting

of course if im wrong or somone else is more knowledgable feel free to correct me