There's a bit more to it than that - once reactionaries started saying that 2 + 2 could only be 4, anyone who was woke and knew a bit of maths started brainposting about how actually 2 + 2 could be defined to mean 5 in various ways, and that was perfectly valid mathematics, and the reactionaries were showing their mathematical ignorance - all as a dunk on the reactionaries, not a defence or explanation of the original joke.

I'm not sure how widespread this was. I may be friends with an abnormally high number of radical leftists who like abstract algebra.

This was all mildly irritating, but the worst thing was when some of them said 2 + 2 could be 5 in modular arithmetic.

The whole thing was pointless and stupid. It was perfect Twitter.