As for reporting to the supervisor, you have got to be kidding me. If the supervisor was doing his/her job, they would have seen the incident themselves.
Supervisors can't see everything that happens in a checkpoint. They may be dealing with other things already happening in, such as a ETD alarm or a passenger complaint. The fact is that the supervisor could have been doing their job. Thats why it's on the screeners shoulders to do their job, which is exaclty the hardest thing to do.