So... this user claims to have been given a reason:
"Sorry kabum21, you are banned from posting or sending personal messages on this forum.
You have been permanently banned by a forum moderator, probably due to spam or plagiarism. You may appeal here, but your chances are not good:
banappeals...@theymos.e4ward.com"
Not sure if that's a one-off or a permanent change by theymos. But guess what, still started an appeal asking which post they plagiarized.