Cameron talks to the only person who will listen to her House obsession: Wilson. She doesn't understand why House has a problem with his dad telling the truth. Wilson says that House hates being a disappointment, and would apparently rather be lied to and told he isn't than face the truth and maybe do something about it to help himself. Cameron doesn't see how any parents could be disappointed in their world-famous doctor son. Wilson points out that parents aren't exactly pleased when their kid is miserable. So it's much better to lie and tell your adult son that he isn't dying as opposed to telling him the truth he has every right to know and upsetting him. And it's not like Carnell isn't going to find out; I'm sure Cameron's next move was to go to his room and accidentally reveal it to him.
House revs the engine of his handicapped-parked motorcycle, puts his helmet on, and drives away. The camera pans to a close-up of the handicapped parking sign. Because House is HANDICAPPED. And that's the truth.