Lots of motives, attempting to discern them on a scale of who has the biggest gripe is for the amature detective. Sherlock is looking into who has the technical skills to pull off this caper. Imitating usernames is easy, but who is the master hack, able to log in at will with new accounts?
I dunno, how hard could it be, get a copy of Kali linux, mask your Mac address, proxychain or use a VPN (check for DNS leaks etc) to mask your IP, use an encrypted temporary email address, make new account and you could masquerade until your heart is content.
And now in English, please, even that Broad Scot thing would make more sense.
In the meantime there emerges a new suspect: JamieDelarosa!
The master sleuth of cheater detection.