The carnist claims that eating animals is ok because veganism is a cult
Carnists also claim that veganism has no rigid definition. So which is it: is it a cult where all members walk in lockstep or is it a vague mass with no defined edge? Answer: whatever suits the narrative.
In this context cult is never given a serious definition; it's just thrown out as a meaningless insult. Be that as it may, veganism has no leaders, no financial hierarchy, no enforceable rules, no restriction on coming and going, no restriction on contact with the outside world, and isn't even a single organization with no campus, no founder, and can exist as a single individual living on a desert island as carnists like to point out.
The best you can say is "veganism is a meme" (using the proper Dawkins definition of "meme") or "veganism is an idea", which lacks any real bite. But I think most vegans would agree with this definition anyway, because, yes, veganism is an idea that spreads from person to person as people become convinced of the arguments that support it. And if this website is any testament to it, veganism is a contagious idea because the ideas that support it are good. The problem is that the arguments against it are of poor quality and easily debunked. There are just so many of them. So many.
Ok, let's even assume that "veganism is a cult" is even a meaningful sentence. Does that mean that you now have carte blanche to kill and torture animals? No, that does not logically follow. Plenty of real cults abolish drug use. Does that mean that doing recreational heroin is now ok? Even if veganism were a "stopped clock", it could still be right twice a day.