This is covered in the "Tips and notes" for this section:
"Who looks for me" is perfectly good English, from the grammatical point of view. From the pragmatic side and taken in isolation, it seems, of course, not quite right. But in a very particular context — granted a pretty rare one, which is why the sentence may seem ungrammatical — the sentence is perfectly fine:
– "I think Abby likes you. She looks for you at lunch every day."
– "Huh? Who looks for me?"