This isn't like faking an attempt on his life, and he would be able to play up his recovery for sympathy on some Bob Roberts shit. He got an extremely communicable disease because he didn't take the proper precautions and didn't take it seriously. Even if he survives, there's not much a way to spin sympathy out of that.

Besides, if this was a hoax, the smart play would be to emerge in two weeks and say, "I've seen the light. This showed me how serious this disease is. We're all in this together. I'm pledging billions towards research and preventions if I win." He'd probably win if he did that.

And then after the election he could just renege on his promise.