"He's a shrink. Of course you should be scared of him." This is walking the fine, fine line of outting Hannibal to someone it's potentially a bad idea to do that with. Rhys is close to people like Watson. Or at least he was close enough to go traveling with the guy. Enoch, too. Wilson. These are people who would feel obligated to crow just as soon as anything gets out about Hannibal's true nature.

But House still wants to protect Rhys to the extent that he can. Rhys, Ecks, Wilson... all the people here who don't know.

"Guy makes a living getting into people's heads and rattling around. I never trust therapists. There's always an angle they're going for." This has the value of being true and being non-specific to Hannibal, just the annoyed ramblings of a paranoid and very closed man. "Just don't start talking to him about mommy and daddy, and you'll probably be fine."