Mike, If I know something for a fact, I'll say so. This thread deals with one of those trivial bits that I've never really had any involvement with, so my grasp of detail is pretty weak.
Yet, I would not dismiss the assertion out-of-hand; something sounded familiar. I'm still looking...
I did find that UL treats general-purpose transformers as though the terminations were rated for 60C. I can see where that van easily be exceeded in an attic.
As I said, this thread has me thinking, and looking.
And I agree; you don't 'cite' unless you CAN cite!