The question of dealing with unique events, while interesting, is not important.
The real question is will computer pilots increase safety and the answer is almost certainly yes.
I think you are missing the point in that if we go to autonomous aircraft all that happens is that the safety risk shifts from one risk to another.
Whilst computers may do a whole bunch of things better than humans the middle of the Atlantic or the Indian Ocean at F370 in the middle of the night is not the time to find out some bizarre problem with the autonomous machine that no one thought of. Presently if that happens the human can always hand fly to the alternate. QANTAS has had at least 3 incidents which were 'never supposed to happen' that I can recall off the top of my head.
If you look at the accident rate of Western Airlines you will find the accident rate is ludicrously low and the fatality rate is even lower.
The questions are:
1. Can autonomous aircraft beat that fatality rate?
2. Can they do it cheaper than pilots do now?
Single pilot airliner ops in the future are probably going to happen.
Full blown autonomous airliners are probably going to be deemed to much of a risk and I would suggest that regulator and/or insurance companies will probably make it difficult. Regulation is something that the tech industry is not particularly used to dealing with or does very well.