I hope you are seriously joking or at least being sarcastic as otherwise you sir are a troll of the highest order. If you are saying out of principal you would turn down a shot at putting an Everton jersey on and walking out onto the hallowed Goodison turf to play in a game. Just because Koeman is boss.
Even though it would never happen i think 99% of us on here wouldn't care who the manager was if they were willing to give us a shot to play for the team we love since the time we could walk and talk.
The irony is for all we know Barkley can't stand Koeman maybe never and especially after the way Koeman has treated him. But did he refuse to play or stay on your morale high ground no he still wanted to turn out every week and play for the blue of Everton. Yet you would turn down a shot? Ok then.