I think it is proper for anybody, President to handle their health how they choose and in private. That is why we have a second and third in line for the oval office right now.
Your over 60 I'm guessing, I'm sure you know some old timers that don't go to the doctor because they don't want to know. My father was like that, never went to the doctor. He got taken out of work at 60 on a stretcher. Health was so bad he never worked again and died at 66. My uncle said it was an old Italian thing. If he didn't go to the doctor nothing was wrong with him. Not the way I am and I'm sure Biden is not that way but he might not wanted to have the test and I don't blame him.
People should deal with their health how they want to.