For all intents and purposes, he is the commissioner. But someone else may be identified as the official commissioner and this coach may officially be an assistant commissioner or something like that. Bottom line, it’s easy to create a loophole.
Also, naming the players to the all-star team isn’t the issue … the issue is playing his plays preferentially over our players. For instance, my second son never made an error at second base all year. But he was moved to outfield for all-stars and a player from the other team is playing second base. If our coach was the all-stars coach, it would be the other way around. It’s not a criticism of the coach … it’s just natural bias.