My takeaway is one needs to understand (as the question reads) what constitutes "A flight control failure" which is defined as either a hardware or software issue.I guess my key takeaway would be the difference between "fly away" and "loss link". I'm guessing if you lose link and the drone RTHs, you're good. If you lose link and the drone flies away, it's an NTSB issue.
Not Loss of control due to pilot error; Loss of control due to operation outside of aircraft envelope; or Lost Link