I don't know how he have 100s of accounts,even you didn't provide link to any accounts
Dude I guess it was only a hyperbole. He only used the term "100" to describe him for having numerous accounts. That's only my own opinion, who knows if he really own hundreds of account?
Maybe you need to check the transaction details to prove other accounts or it won't get tagged.
You have a point, much stronger evidence is needed to prove him guilty. But actually, the presented evidence by OP was already an effective one because logically thinking, the email on his posts definitely belongs to him thus having a big chance that he also used it for scamming people.