Helping the government in general != helping one specific government agency with a narrow mission. Maybe you could provide an example of a government program/agency whose mission you consider somehow "opposite" to ICE.
But sure. Helping any entity accomplish a politically controversial activity is a political act.
Yes. If IBM built something that helped the government during the Obama administration, would you consider it "political" too?
I think we should admit that, and then say, it's okay for GitHub employees to say "My employer's politics don't agree with mine, so I'm not going to work for them anymore," and for GitHub users to say analogous things. My point is that it's deliberately deceptive for GitHub to hide behind the claim of being apolitical.
Obvious hyperbole but you get the idea.