Funny you mention that reputable source, when they stole that care sheet from someone else and even put their own name on it.
I have kept my baby at 89-91 degrees. He has shed and eats great. (note, he's not dead)
I'm not saying I have it right or you guys have it wrong. But typing on a public forum, 91 or 85 degrees will kill a BRB is ridiculous. I know two local breeders and they both approve of my setup. I know them in real life. Not some website.