As for the bit at the end that even a slight improvement would save a lot of lives worldwide, there's a lot of people who would not be able to afford what would undoubtably be a very expensive tool so the potential impact is vastly over stated. That is of course assuming that it ever gets to the point were it is actually useful.
I would agree with you that such a statement doesn't quite pass the smell test: it seeks to explain away what is really just noise in the statistics. That doesn't mean the approach cannot be of value, but if so, they're not exactly near it being of any practical use - more work required.
However, it may just be an area where AIs are not really the best tool, so I would not discount all use of AI in medicine. I am presently looking at an application which is so seriously *not* just statistical noise that I'm excited for it to get funding. That said, the AI's job in this case is more correlation of information, detection happens much earlier in the process. I think that's where AIs can add real value: as PART of a tool chain, not as sole active component.