He opted out of his contract - making himself a free agent.
http://www.49ers.com/news/article-2/Colin-Kaepernick-Opts-Ou...
This is like quitting your job and complaining you don't have a job.
http://profootballtalk.nbcsports.com/2017/05/31/john-lynch-4...
"We gave him the option, ‘You can opt out, we can release you, whatever.’ And he chose to opt out, but that was just a formality."
https://www.sbnation.com/nfl/2017/3/1/14599712/colin-kaepern...
There's a lot of other issues here - it's unfair to say he got "fired" because of what he did last year. He's been very bad lately - huge dropoff since he went to the SuperBowl.
http://review.chicagobooth.edu/magazine/winter-2014/how-gary...
And, as a consequence, the US now has an immature tantrum-throwing child as President with a GOP doing nothing but enabling his worst actions.
Do I think this guy should have been fired? I dunno. Not sure. I need more context.
Am I upset he was fired? No. That's Google's choice, regardless of how good a choice it is or isn't.
It betrayed a spectacular lack of common sense and judgement for someone in a senior[1] role - which is exactly where you'd want those in spades. Also made his working position untenable since a senior role is going to need to get along and interact with many people. Also, also, his utter disregard for evidence and inability to make logical arguments would give me great pause as to his usefulness as a senior engineer.
I'd have fired him first for being an idiot, second for his bullshit "scientism", and third having reprehensible views.
[1] Disclaimer: I don't know if "senior" within Google is the same as "VP" in banks, ie just a defacto title you get after a while rather than a mark of actual competency.