Putting aside rather you agree with Kaepernick kneeling during the anthem and looking at it strictly from a business standpoint if you were an owner would you sign Kaepernick?
That's kind of thing about collusion. If you have 30 teams in the NFL thinking like you just said, and you have two teams contemplating signing him... the other 30 teams are not going to want the other 2 teams to do it. Why? Because if he plays well the other 30 teams are going to look bad for not giving him a chance because of the political ramifications. So the 30 owners are going to reach out to the other 2 teams and ask them not to sign him... to protect the NFL shield. If you don't think the owners stick together, that would be naive.
SF decided to go in a different direction and cut Kaep who was the QB for a 3-13 team. If the 9ers gave up after investing that many years, why would another team sign him as a starter? Why would any team pay $10 mill. for a back up QB, when you can get one for $2 million or less? These are the issues you keep avoiding, its because they are legit questions and prove that there was no collusion among owners. Many teams passed on Mixon because of his distractions. NFL teams don't want a distraction, unless the distraction is offset by talent.
You brought up Vick, he signed as a back up for $1.6 million, a few million less than what Kaep was asking. Ray Rice might have a better case for collusion, but don't let facts get in you emotional rant.