Dave I wished I remembered more of my steel processing lectures from college. They made us Electrical Engineering majors sit through that stuff, and we knew we were never going to use it.
I think I remember some of the details from a project of making new J hooks for my panniers that involved heating the bent hooks up to 400F, followed by an oil quench, and then annealing them at 250F for 20 minutes. I think British Racing Green baked at 275F, and I think there were colors that baked at over 450F. So baking a frame at 500F could anneal stuff that was meant to be tempered. Unfortunately I just don't remember very much about heat treating steel, and that is why I left it as an exercise for the reader. I just don't know the effect on a steel bicycle frame.
I do remember that I contacted Reynolds, and they OKed the melting point of the paint I chose on my Reynolds 853 frame. Some paints need a much higher temp and that is why I avoided them. I don't remember being told limits. I will also concede that Reynolds 853 is more problematic than whatever steel is in the 970 frame.
Bottom line is that I still feel that it may be more complicated than what you have stated, but I am not able to defend my position. There used to be a guy on this forum that seemed to know a lot about chromoly steel, but I have seen a post from him in at least a year.
I still vote for leaving this as an exercise for the reader.