If you hang out in a bar with KKK memorabilia everywhere - and open the replies of any reasonably popular news story on X before complaining that's not a fair comparison - people make conclusions off your presence, even if you're personally there for the tasty beer.
It's an analogy. You'll find plenty of neo-Nazis and bigots of all kinds in the replies of any political post, posting away happily to their echo chamber.
So we know why they did it. They wanted to take a stance against X. They just didn't have the balls to say it out loud or the dignity to leave quietly.
what tradeoff?
What cost is there to post on X at the same time as the other platforms? Zero. It’s not like they need to moderate forums.
We all know what the people defending this are doing it for and EFF barely plays into it at all. This is Musk Man Bad, nothing more.