Kaepernick went 5-2 as a starter in '12, with a QB rating that put him 8th among qualifiers.
However, from '13-'16 he ranked 21st, 20th, 31st, and 17th. His 49ers went 12-4, 8-8, 2-6, 1-10.
He is 3-16 as a starter over the past two seasons, with a middling ranking. The question, then, isn't why he isn't signed, but why any team would bring in the PR nightmare that Kaepernick, recently a middling QB, has become. Nobody colluded to make him that, he brought it on himself. in essence, Kaepernick's behavior shined poorly on his employer and other potential employers noticed. They have every right to do so, btw.
Really like the Tebow comparison, doc. And I'm with Matt, I'm just choosing not to watch.
And btw, it may well be the case that the point of Kaepernick's protest is just mostly wrong: A great read:
http://www.nationalreview.com/article/451466/police-violence-against-bla...