Apologies for steering your thread into charged political territory, but this is one of the biggest reasons I think Zuck and other Valley CEO-types love the H-1B system so much and constantly seek to expand the H-1B cap, e.g. Zuck's "FWD.us" PAC: https://en.wikipedia.org/wiki/FWD.us
Disagreeing with one's boss will always have a "filter" when it can mean having to leave the country if tensions escalate into something employment-ending. Why risk it when you can just write the code, collect your pay, and get to live another day in the country you call home? I could never blame someone for making that safe choice.
Disclaimer: this is not a criticism of any H-1B individuals, many of whom I am lucky to count as my inspirations, peers, and friends :)