Or maybe that's just their defense mechanism? Like a squid spraying ink. When they don't have anything concrete to say they instantly complain about manners?

Yeah that's it. I've worn down enough of them to see the pattern play out time and again. After that comes aggression and insults and if then you get "lol you triggered?"

My favourite thing to do is to ask them a simple question and then point out how they never answer it.

My second favourite thing to do is to explain why Wikipedia isn't a good source.

My third most favourite thing to do is take a shit so big it tears my asshole in two. Gotta eat less fiber I guess.