It is their game, they can ban anyone they want to for whatever reason, they don't have to have 100% legit proof that was not obtained via breaching any TOSs. Also, just to throw out there, in criminal cases illegally obtained evidence can be used as long as it wasn't illegally obtained by the prosecutor, but by a witness or something.
Plus, if you just do a google search it brings up tons of info on sythe, you can get lots of info on sythe without ever entering the website.
View the cache here: All this info without an acct on sythe, and without ever entering the website.
http://webcache.googleusercontent.c...d=1&hl=en&ct=clnk&gl=us&source=www.google.com
EDIT: The only thing I can think of in how they connected it to you is if you ever had any of your accounts linked to that email. Otherwise, they probably have ways we don't know about. We need to get someone to go to London and infiltrate Jagex by becoming a J-Mod!