They were not banned or suspended.
After the patch on Tuesday to massively change the AH, it was bugged and providing lots of gold it should not have been.
See this bug report thread.
Blizzard quickly closed the AH for a few hours to try to fix it. Some players who were impacted, through no fault of their own (in most cases), had their accounts locked.
The locked accounts can not play right now and are undergoing what I suspect is a manual review to reverse damage. Any subscription on the account was removed to prevent billing while the account can’t be played.
Those accounts that abused the bug to exploit it may end up with a suspension, but right now that has not happened.
There is no ETA on when the locked accounts will be freed up again. Hopefully they provide compensation to those impacted players. This was not their fault and they deserve at least game time, if not more. That decision will be made about what compensation, or how much, after they know the duration of the locks and come up with a policy.