It was introduced by ryan seacrest as Chris Cornell’s version of Billie Jean, so an effort was made to give credit where it was due.
Yep, I heard Seacrest introduce it with credit to Chris Cornell. Still, everywhere I visit on the internet David Cook is being praised for the originality of his arrangement. I’m thinking most people didn’t hear Seacrest attribute it during the intro, or Cornell’s name is so unfamiliar to listeners that its mention during the intro didn’t register.