Don, I think you've hit the nail on the head. I agree, no way would a non-essential person be allowed to fly on an aircraft entering hostile territory. Further, as you said, the fact the aircraft took off, flew the sortie and landed back at home base lends further credence to your statement. Guessing there was something peculiar going on in the outfit that caused senior leadership to decide a flt. eng. was necessary.
My first five years were in a B-47E wing. The last three years were as a crew chief. Strange thing I don't remember ever washing my aircraft. And don't remember where the wash rack was. In my defense, I don't remember what I had for lunch. However, my next three assignments I vividly remember washing mine and other acft. … repeatedly. By the time I got to CCK thankfully had been promoted out of the wash rack crew. The 374th was doing it the smart way...by contractor.
The one thing I remember well that you didn't mention was KP. The worst ass chewing I ever got was by the mess sergeant. Seems I left the potatoes in the peeler too long and they came out the size of golf balls.