Its not the uncontrolled part that would worry me
Operating a 121 flight into an uncontrolled field is not a big issue. They would have being in radar contact with Potomac and on the CTAF. There are locations in the US, Steamboat comes to mind, where you have RJ's etc operating into uncontrolled fields with no radar coverage. It is not unsafe to do this as long as that is the plan.
What would have worried me was, why is the tower not responding? It seems no one could answer that and I would have diverted. A lot of strange things can happen. At Newark the power and the back up to the tower was cut by a pile driving crew. At Hartford there was an incident where an MD-80 ingested tree branches on final. The root reason was ultimately bad glazing in the tower cab!
The point being, if something isn't right I'd want to know why before heading on in. It may well have being they had company info from the ground that everything was OK. What surprises me is that the Airport security was not sent to check the tower out.
20driver