I view what Blackshear did today not much different than showing up for warmups and then leaving to go catch a movie.
Is it his right to ask for a redshirt? Sure. I don't even disagree with him asking for it. But you do that before gameday.
You've practiced all week with the team for a game, and then decided to bail on them before kickoff without any chance of installing an alternative plan. You've allowed a gameplan to be installed that relies on you doing your part, and then decide to let your team swing in the wind without you?
Definitely should be stripped of his captaincy, without a doubt, at the very least. Those aren't the actions of a captain.