It sounds like x10Hosting does not like access to its systems through a TOR connection. The TOR connection created the "substantial link" between my account and the account with the "history of abuse activity". Though, I didn't see anything about origin of access in the Terms of Service.
I received a suspension notification recently, so I authenticated with the x10hosting login page and received this notice:
Access is restricted to your hosting account. The restriction is due to a substantial link having been discovered between your account and another account with a history of...