I don't think they can, but usually an HMO doesn't cover "pre-existing conditions". Also, I think their corporate insurance rates are based on the pilot's being healthy to a certain extent.

that said, I got a letter from them saying that my hearing is deficient "though within FAA guidelines" and I should see a doctor (6 deployments with the Navy will KILL your hearing, and I wear double protection all the time!) to see if any follow up is required, but "the results of this evaluation will not affect your job offer."

So, interpret that as you will....