This is bullshit.
He's been on the Boston Mythos Squad for fifteen years, which means he's gone through twenty-nine screenings for Mythos exposure disorder, and every single time it has turned out that he doesn't have it. At this point, he's clearly immune or something, so they should stop making him go to therapy when he could be dealing with the, you know, numerous cults bent on summoning extradimensional monsters.
(He needs a shot of whiskey to wake up in the morning. It's fine. No one winds up making a deal with Nyarlathotep because they're an alcoholic, and if he lives long enough to die of liver failure he'll count it a win.)
(Everyone who was on the force when he joined is dead or disabled or retired or insane. They've started to call him the lucky drunk.)