>But then autism research took a badly wrong turn.

I agree, it looks awful. But I think it is wrong for another reason altogether. I'll try to explain it but I am seriously bad with the proper grammatical terms so be forgiving please. Here goes.

Isn't "wrong turn" one concept, one, ugh I don't know if noun-phrase is the right term but that's what I'll call it. It is the same type of thing as an "upper hand" or "upper body" - these are “one” thing.

In the sentence they are qualifying only the word "wrong" thus disregarding the actual noun-phrase.

It still wouldn’t be pretty but saying the research took a bad wrong turn seems better to me.