I'm sorry you're being downvoted for this comment. What you're saying is absolutely true, the moderates just don't want to hear it.
It's the candidate's job to assuage voter's fears and convince people to vote for them. If Biden is too frail to do interviews, how is he going to do an election campaign? How is he even able to do this job? We have other people, why does it have to be Biden?
I liked how Jon Stewart put it - when the barbarians (Trump) are at the walls, you want Conan up there leading the charge, not a feeble old man who's afraid to appear in front of the public.