In here, you can't appeal for friends (they have to do it themselves) but i will make an exception because this is a very simple case.
1) He's lying
2) He is the developer of abuse tools for "SeeMTA" server, such as bots and Anti-AFK tool. These tools have been detected, and he, being the developer, got a ban for being behind that stuff.
Temporary bans cannot be appealed, and lies won't change that. He gotta wait until it expires.