I think my point didn't exactly get across. I'm not saying philosophical zombies can't exist because subjectivity is something beyond information processing, I'm saying it's plausible that subjectivity is information processing.
To say "a person with information processing but not subjectivity" could be like saying "a person with information processing but not logical reasoning".
I would argue a person that processes information exactly like me, except that they don't reason logically, wouldn't process information like me. It's not elevating logic beyond information processing, it's a reductio ad absurdum. A person like that cannot exist.
I was saying philosophical zombies could be like that, it's possible that they can't exist. By lacking subjectivity they could inherently process information differently.