I don't think jail is required here, I think a simple "don't do it again would suffice". It is not like he intended to disrupt the entire city.
I have the similar issues trying to keep my kids focused during the school day. I finally found a way to block him that didn't block my job access, and turns out all the kids are passing around VPN accounts to get around parental locks. For all my work I only managed to keep him off Minecraft for ~45 minutes.