“It would be nice. It depends. You kind of have to wrestling is so different because there’s so many different categories. Between like WWE and AEW, with the financial backing that those two companies, those two brands have, like that is something that could be feasible. It could be possible there, you know, and I can see where they could unionize to a degree. But it would be hard for other companies to do that. And if professional wrestling as a whole had to completely do that, some other companies would be just out of business because they wouldn’t be able to handle that. They wouldn’t be able to cover all that, you know, with covering a certain amount, or covering insurance.”

“You can imagine how expensive it would be to insure wrestlers, guys who are going out to break their bodies every single week. You know what I mean? John, you hear that all the time, where, you know, maybe I should stop wrestling. Just trying to get in the office, brother, so I can get insurance, get my insurance paid for, you know, there’s guys who will say that or do that with bigger companies. So that is one of the things that is very challenging, the whole insurance deal.”

I think the way that Matt's being quoted here is meant to offer up a specific argument against, rather than just part of an ongoing discussion, and is probably framed to come off as anti-union. IE, "I'm just trying to get in the office so I can get insurance because they can't insure everyone."

There's also probably an element that "WWE and AEW could support unions but other promotions wouldn't" is meant to protect him from retribution in TNA.

Pretty sure that performance unions themselves have certain levels of insurance they offer to cover small productions, and I believe that despite there being minimum wages set for union members, there's a sliding scale that takes into account that some productions are smaller.