Firstly they haven't actually stripped him of the captaincy, weren't they letting the players choose whether he stayed on or not, but even if they did, I'm not sure he would care that much, he's not you're committed type on the pitch or a leader, it would probably be doing him a favour.
IMO he should have been fined, best way to hurt these guys is in their pocket as they don't care enough on the pitch these days.
Also they confirm he isn't being discipined here:
https://metro.co.uk/2019/10/30/arsen...alth-11009608/