The crazy part is that:
1. No verify-names
2. If the rules don't say anything against what he is doing, then he probably isn't doing anything wrong and plus, as icanttellyou stated before, people could be impersonating, and how do you know he has alts if you have little evidence or even their ips.
3. If you don't like the server, leave the server.
4. If the owner really gave a sh*t, they would have banned or even ip-banned him.