He had already been cut several times and then began taking a knee to bring attention to himself.
While he's a douche bag for certain - the above is simply not true. He opted out of his contract in SF to pursue free agency - and was never signed.
All NFL coaches will tell you they will do anything and everything in their power to minimize distraction(s). And he'd be a huge one even though he's still better than some of the backups in the league.
If you google Colin Kaepernick, it lists "American Activist" as his occupation - not NFL football.