I would call that enforcement of a term of the service.
When I said arbitrary terms of service can't be enforced, I meant that the site owner won't have good luck trying to obligate users to do things (their typical response to a problem with the user will be limited to withholding access from the service). I wasn't very clear.
When I said arbitrary terms of service can't be enforced, I meant that the site owner won't have good luck trying to obligate users to do things (their typical response to a problem with the user will be limited to withholding access from the service). I wasn't very clear.