Considering what we've seen and what he knows about BOB there's no reason for him to consider that BOB is a doctor, so why does he ask?
I have a theory and it has to do with the extended ending of the Pilot, where Mike says literally that BOB "sometimes work among the infirmed, the injured of the species", so maybe that's where he got it... If the writers of ep.4 still considered the extended ending to be Coop's dream like in ep.3 (with Lucy, Harry, BOB being shot and Hawk doing sketches) this could be the answer and why Coop thinks that...
Any thoughts?
