I think you can only block people from commenting on your games, and only after they commented once. On the other hand, if you enable a community for your games and/or jams, you have full moderation powers over it, band included.
Viewing post in Is there a Block Feature?
How do we block games/content from creators? re: my reply to the thread itself, below
"Yeah, I'd like to know how to block games. I know I can block content creators via their profiles, but it doesn't seem to block their content. I don't want to see pro-pedophilia porny shit and since mods on this site seem to think it's okay to exist, it'd be nice to be able to block."