This is EXACTLY why two man crews are important.
This!
The CROR Rules in Canada require that the first crew member to identify a fixed signal call it out in a clear and audible manor and all other crew members repeat it back. I imagine the eastern US has the exact same rule, but it is impossible to comply with when you are alone...
It also puts responsibility on the Conductor to ensure that the engineer complies with said restriction.
Having that second set of eyes/ears would prevent tragedies like this...
With so many accidents in recent years caused by the negligence of single man crews, this seems like such a simple solution that could save lives...