I'm no fan of ICE – a very large percentage of my friends in the US are immigrants, and I generally want my country to be a welcoming one. ICE has certainly committed unethical and probably illegal acts (probably true of most federal agencies).
But to expect that a _federal agency_ will be denied service from a private entity, especially for essentially political reasons, is lunacy. It'd attract extreme negative attention from the rest of the government, and great fear from all paying customers that an internet mob could separate them from their code at any time.
We should absolutely be lobbying hard for changes to immigration law, the restrictions placed on ICE, and justice for their wrongdoings.
But I can't see how this helps improve immigration, and it certainly seems likely to cause a lot of negative consequences for GitHub. The employees are putting their employer in a "damned if they do, damned if they don't" situation.
EDIT: Just to clarify, I love the vision of a world where executives don't take actions their workers will protest. I think that in order to get there, the protests need to be reasonable, and I think this one isn't.
EDIT DISCLAIMER: I own a small amount of MSFT stock, which was not on my mind as I wrote this. I use GitHub's free service and have no other relationship I can think of with MSFT or GitHub.
Um, think you've got this backwards. Private entities shouldn't have to take on anyone they don't want as customers (for whatever reason - do you have to justify who you do or don't want in your livingroom?), but publicly-funded institutions shouldn't be able to deny service on political grounds.
In free societies, governments should only be able to forcibly compel people not to do things (murder, threaten, steal, etc.) - see the concept of "negative rights."
The great thing about this, is that someone else will realize there is now an under-served market, and create a business to fulfill that need.
The same case can be made for hiring practices.
That is a childishly simplistic understanding of how free markets work. There is no way a retail business would be established to service the needs of 2% of the population who are wheelchair users for example, when they could easily make their stores considerably more efficient by making the aisles a little narrower.
I bet most businesses would make their stores accessible (within reason) since you need room in isles for carts, etc.