I know nothing about aerobatic display flying: Do such pilots have to pass 6 monthly aerobatic flying exams in the SIM and/or the real aircraft? We, (normal airline pilots), do, though not aerobatics !
Secondly, just because someone is highly respected and very experienced, does not mean that they somehow magically retain their fine flying skills for ever, i.e, reaction times, hand-eye coordination and SA during unusual attitudes. At some point in our lives, our brain power starts to diminish.
I would hope that display aerobatic pilots are very rigorously checked indeed - including medically, for example proper eyesight examinations and their 'g' resiliance.