The reason he has a banned account on his IP but he still got Mod is because Jagex will only not invite you if they can prove that the botted account was yours. They really can't.
The only way to really prove the same creator would be same email, recoveries, bank pin, and passwords.
Potential Mods are really only "noticed" via 2 Methods..even after you're noticed you have to be "PMod" material to get an invite:
1. Attend Events Regularly with JMods Acctive, Posting regularly in the Events Forum and having a helpful, positive attitude, Report accurately, and play the game normally.
2. Player Moderator Recommendation