Who says Microsoft isn't doing more good than harm by helping ICE? ICE will do their job regardless of the tech they use and for all we know, Microsoft is helping ICE reduce mistakes which would otherwise harm the people that ICE needs to manage.
People in general need to be more pragmatic, because we see a lot of emotional reactions which only make things worse.
I always find this argument unconvincing. At its most extreme expression you end up with obviously bogus propositions like "Islamic terrorism is going to happen with or without you, so you might as well join ISIS and attempt to reform them from within."
It's probably unwise in this case to transplant one argument for another and then make a decision about one based on the other instead of assessing them independently. ICE is not ISIS. Illegal immigration is illegal just about everywhere on Earth and for good reason. ICE are simply the enforcement arm of that legal construct.
Interestingly enough, ICE and the border patrol may further reduce the chance of ISIS attacks in the US as ISIS explicitly stated they wanted to hide among undocumented migrants to sneak into countries at a larger scale.
Life is messy and sometimes the solutions have to be too. It's a great place for software to try to keep things as clean as possible.
People in general need to be more pragmatic, because we see a lot of emotional reactions which only make things worse.