Removing the Oklahoma tag from his personal social media account is about as small a thing you can do. He's not qb1 there anymore. It doesn't even mean he's leaving for sure, just that he's not their QB, which is true. He certainly hasn't announced he's actually transferring or anything.
Let's be real though - he has no choice but to transfer if he wants to play enough to reach his dreams of making the NFL. If he were your kid, that's what you'd tell him. Backups don't get drafted. Riley and Oklahoma knew that, and they obviously thought he was better than Williams but now have a problem because they put in Williams and he performed. So cfb fans are reading tea leaves with his social media.
I don't think recognizing reality makes him a headache or a Prima Donna. He's not out boozing every night like Manziel.
Whether or not he's actually good enough to make it is besides the point. Not transferring is not trying, and actively hoping Caleb Williams gets hurt. That's not good for anyone. He is good enough to start at lots of P5 schools right now.
If you transferred him in in the spring at Iowa, he competes for the job with Petras in the fall, and worse case scenario for him has two years (probably one) as qb1 for a team with junior/senior tackles, a junior center, and a junior guard if he doesn't beat out Petras, and a pretty good defensive line, or he transfers to a team that guarantees him a starting spot, like say, Ole Miss or Cincinnati or USC.
I'm thinking of this like a baseball trade.