"When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong."
The human body is a meat robot. There's no reason, in principle, why it couldn't be maintained in working order indefinitely. Whether we'll see that in our lifetimes, that's a completely different question. His argument basically boils down to "it's a complicated problem and there's a bunch of snake oil salesmen in the field, therefore it's impossible to solve". Debunking bullshit is of course praiseworthy, but to claim that the problem will never be solved seems to me like throwing the baby out with the bathwater.