They can stop you from doing any work on the project. They can even fine or jail you for work done after the law takes affect that the international committee doesn't allow. Which is to say you can be forced to stop work.
Though if you don't live in IL it is unclear how this affects you.
Can someone who knows the law explain to me how someone who lives in California, and hooks his computer in California, to a wire in California, from a company in California...
At what point do they become subject to Illinois law?
And can Illinois prosecute someone for doing something that is legal in California while they are in California?
Governments can hire a hitman to go after you, if you say something wrong. So can international crime syndicates. Will this have a meaningful effect on chilling your speech?
https://abcnews.com/amp/US/children-recruited-criminals-indu...
Some time in jail or having to fight a fine for refusing to implement features in the constitutionally protected free speech code they author? If that is what it takes.
I do not want to go to jail, but if that is the only way to get to an outcome where people have confidence they can not be forced to add unwanted code to open source projects, so be it. But that is a pointless thought experiment because it will never happen.
I do not think anyone would be stupid enough to jail a FOSS developer for not agreeing to compelled speech, and if they did, an army of lawyers would be lining up to take the case I expect, with the full support of the public. It would be an insane thing to attempt.
We must loudly push back on the chilling effects intended here. Our free speech to write or not write any code we want will not be compromised.