The whole affair seems to me a severe overreaction considering they could have just sat the guy down and talked the issue through.
His tone and mentality feel a bit confrontational (and we're only hearing his perspective), and mentioning the skin color of various people involved seems anachronistic, but...
... at a smaller company, maybe the boss would have just sat down and had a talk with him "look, these people get good wages, and we're keeping the jobs in the US" or whatever. It doesn't sound like it was handled in a very "human" way, where someone directly above him who knows him was given the authority to straighten things out and make sure no further problems occurred.
Legal...security... all starts to sound like "lowest common denominator", and a good reason to work at a startup or small business rather than a large corporation.
(Edit: not that legal, security, etc... are not needed or don't do useful things... it's just inevitably a bit bureaucratic)
Likely that way now because he was fired. If it's true he was going to quit soon, and had he done this all the day before he was leaving to feed his curiosity, maybe the tone would be different?