I have no reason to believe it's fake news. One thing we need to consider regarding how this turns out is that the quality of medical attention he receives will exceed that of other obese 74 year old males that contract the virus.
If he beats it, that does not mean it is not deadly. Available, top notch medical care comes with being President of the U.S. That type of care is not found in the vast majority of hospitals and communities in the U.S.
If he gets seriously ill, or even dies, there is so much unknown about this virus that would not really tell us anything new either. Even among at-risk groups, the virus hits some harder than others. We don't know yet which side of that fence the President is.
And, as we know, many people that have the virus are asymptomatic. He could legitimately be one of those as well.