If I was an American Citizen....
I'd regard this as a matter of potential "national" security, certainly if there is a real vulnerability then the safety of citizens (also tourists, visitors etc, all human beings but sadly not necessarily benefitting from the protection of some US laws as they seem to be interpreted at the moment) seems to be in potential peril. Given the amount of people who hate the USA and want to create genuine terror (not the sort that in the UK treats dressing up as Batman and standing on a window ledge as being on a par with the PIRA of the '70's) then this vector of attack must be up on the baddie's "to do" list.
It might be nice to think that if there was a government body with the sort of technical/management skills to perhaps help advise the ATC operators how to reduce or eliminate this risk (also the risk of things like power stations and other essential utilities being disrupted electronically), in the interests of general orderly management of the country, that it might do so. Some sort of "Agency" dedicated to "National Security", or somesuch.
I seem to recall that even Machiavelli's Prince advocated "first; look to your defence".
Now it may be that highly technical minds have determined that there is no genuine risk. I'm not sufficiently qualified to determine that, however if they're wrong, then it's a terrible indictment of their ability to correctly determine the threats from which they should be protecting people. Ultimately the only real judge will probably be history (ooh, there's a joke there, must work on that one....)
Even so, it might be nice if such an agency could issue a reassuring note to the taxpayers funding it that their interests are being looked after in such a regard. A bit of joined up thinking in government perhaps?