Sealioning is totally a thing. Another thing (which to my knowledge doesn't have a well-known name) is accusing someone of sealioning as a way to deflect from having said something that could really use to be supported, while refusing to support it.

"Pi is not transcendental!"

"Wow really, I'd love to see the proof of that!"

"You're just sealioning!"

I'm not making any claim about which of these two patterns is more common or a bigger problem, but both things totally exist.