Well I'm not a pilot, a lazy eye prevents it so I apologise for my ignorance but do the Army have qualified pilots for Watchkeeper/450?
A good friend of mine (my son's godfather) was up until recently an F15E WSO, told me that his problem with UAV operation, especially at altitudes less than 15000 ft was that operators may not have enough or relevent experience. The chance of an accident or at least an incursion preventing a manned platform from deploying a weapon could exist. I think the American army will use unqualified "pilots" for it's UAV's which at first site is worrying.
I know watchkeeper is a shorter range, line of site vehicle but it seems to me that there could be a risk. It must inspire a degree of confidence to know that the people flying the platform, are are suitably qualified and competant to do so, as in the case with 39.
As an aside, wouldn't a operational pilot who has failed a medical be a pretty good candidate?