Do You Like This Wallet?

It's nice, but it seems too long if he wanted to put it in his backpocket. I know you said he carries a messenger bag, but I feel like guys I know like to carry wallets in their backpocket.

Just my opinion, but I'd pick a smaller one.
 
I would go with a smaller one as well. So he has the option of carrying it in his pocket when he is not carrying a bag as well. In my opinion I find the longer wallets more feminine.