I don't think it is about political pressure in the sense that, I doubt the USG fundamentally cares about whether or not Iranians can use GitHub or not. For com

I don't think it is about political pressure in the sense that, I doubt the USG fundamentally cares about whether or not Iranians can use GitHub or not. For companies like Google or Microsoft, this is about minimising the attack surface because they do other (legal) things that the USG does care about. You can't punish a tech giant just for doing a tech giant, but you could try to make other things stick.