He's essentially talking about the imperfect cell division which leads to increasing amount of "errors" in average cellular structure over time, and that if this is the most important cause of aging, future studies should be focused at molecular level (which is typically the domain of physics).
Here's an excerpt from the conclusion:
> That doesn’t mean there is nothing we can do. More research into specific molecular changes in aging is needed.
I don't see how his thesis addresses the very large difference in lifespans for different species, first and foremost.
Secondarily, although he addresses the body's repair mechanisms, I don't see how he puts a new limit on their capacity, unless I overlooked it, or unless he thought things like the Hayflick limit etc. perfectly address that (which it does not completely do).