Fred put his health issue out there first, because people wanted him to run. He didn’t think it was a problem, but practiced full disclosure on this so people could make up their own minds. I admire how he handled it.
If it was a problem, people could have brought it up before when he first disclosed. Some did, many did not.
It is a judgment call for everyone involved as many people go in remission, and often it never comes back. I have a dear friend who was a cancer patient and is doing well forty years later. You never know and hope for the best.
That said, some will use it against him no matter what. This has been discussed rather thoroughly. A person needs a little humor in this grim world.