Free speech absolutism is harmful. By remaining federated with them, you're participating in distributing their content and giving them a platform. People do have a choice of what they want to see, they can choose to be a part of another instance without morals. I would hope that a programming instance of all places would understand the consequences of propaganda given so many programmers work in data collection and targeted advertising. If you show an ad to 1000 people and one of them buys the product, the ad worked. It's no different for disinformation campaigns.
It's not like they're just sharing differing opinions or saying awful shit, they're taking things out of context or making things up (or posting articles that make things up) and it's very easy to prove if you do a tiny bit of googling. One article listed off a bunch of climate predictions that were wrong along with sources to look credible. If you checked the sources though, they were all wrong. Some of the predictions were actually made by humans (but not the claimed academic institutions) while others were straight up made up.
I hope the admins make the right decision here. Protecting free speech doesn't mean allowing people to say whatever they want on your platform. It means allowing them to say it on their platform without being fined or put in jail.
Go find me a left wing instance that spreads hateful disinformation and incites violence and I'll ask to defederate with them too. Just because the right is the only side doing it doesn't mean they'd be removed for being on the right.
If someone goes to jail because they murdered someone, it wasn't because of their political preferences.