My opinion on Kap is that the reason he doesn't have a job right now is actually not incredibly different from the reason Tim Tebow isn't in the NFL anymore. Yes, Kap's protest is absolutely affecting his job status, which sucks, but it's more than just the protest. Kap is still not a very good quarterback and there's enough statistical evidence to support it. Since he's been to a Super Bowl he's not going to be cheap. And he's not a conventional pocket passer, which makes him kind of worthless as a backup to a conventional quarterback since the offense would need to be restructured to suit him should Kap need to enter a game.
So basically, he's not getting a job for similar reasons to Tebow. Nobody wants an unconventional backup quarterback who isn't that good and has a media circus following him. Kap should get one more shot in the league, especially when you see some of the scrubs that keep getting chances, but I see why he isn't.