My inclination is to say that the a/c was likely not well trimmed, and was only "seemingly" in stable flight, perhaps "hunting" a good deal. Whatever the cause of a/p quitting, UAS or turbulence, the a/c itself made the decision it was not "stable", nor could it be stabilised (by the a/c). This makes a comment like:
"...the airplane was stable before the event and, doing nothing while the airspeeds return will keep the airplane stable. Move it, and you've moved the one "known" in the equation that you had and you've taken yourself into no-man's land with no way back, without a great piece of luck and skill.."
quite patronising, and dismissive of a very likely reason for not "sitting". Also, perhaps a bit biased in favor of the "Platform".