Deal with the problems that kill the most people, then move on to smaller problems. Tired cyclists don't kill the most people on the roads.
That's just whataboutery.
You'll never reduce deaths from motor vehicles to such levels that more people are killed by people riding bicycles, so saying that we shouldn't even discuss cyclists behaviour because there's a greater menace is silly.
Anyway, heart disease and cancer kill more people than motor vehicles. Should we stop doing anything further to try and reduce deaths from motor vehicles until we've cured cancer? Of course not.
A proportional response is required (i.e. much more focus on motor vehicles than bicycles) but that doesn't mean that we can't consider cycle safety. Funnily enough, that's what we're more likely to discuss on a cycling forum where a bunch of long and ultra distance cyclists hang out.
Audax certainly pushes some people to do more than they should, which may end up getting themselves hurt (even if they don't hurt others physically). Sure everyone is ultimately responsible for their own actions, but put an artificial deadline in front of someone and some people will try and push on through where/when it is not prudent. You can disclaim almost everything in law except negligence and I'm not sure that the over-arching competitive push-yourself-to-complete is safe in this respect.
People are a lot more willing to make the correct decision when they are driving as they're far more aware of the damage that significantly greater mass and speed can cause. But it's amazing the number of heads being stuck in the sand when it comes to their own safety riding a bicycle (i.e. the comments about hallucinating when riding for example, I've done it myself, I was seeing things on luckily deserted A7 heading back into England on LEL in 2009).
This is, fundamentally, one of the main reasons why I decided not to organise any Audaxes. I don't want to be responsible (no matter how much of it wasn't my fault) for something bad happening.