Sure they are trained to put themselves in harm's way. But it shouldn't be needlessly so.
One of the most dangerous things a traffic cop can do is randomly stop a car that ends up being driven by a fleeing murderer, who can over react in that situation. If a cop knows the driver could be a fleeing felon they will take precautions and do a Felony Stop. They wait for back up, have weapons drawn and make the driver exit the vehicle, hands over head, walking g backwards.
If this rumour is true, the FBI asked these traffic cops to walk up alone to a car, being driven by a mass murderer, who may be very scared or upset about being stopped. That is an unnecessary danger, because the cops were going to arrest him when he got to PA. Who cares if they check his hands a day or 2 later?
It really bothers me.