Why didn't that experiment start with real old mice? And reversed their age to young again? That could be more convincing that "reversing" ageing of artificially aged mice.
Because they haven’t reversed aging in this experiment and the partial reversal they did achieve was using tools that already exist. The point of the experiment was to prove that epigenetic information loss is the cause of aging. The next step is to figure out how to completely reverse epigenetic information loss.
Sounds theoretically possible. I mean it definitely happens at conception, and methylation happens at specific sites where it should, and not where it shouldn’t. So there should be a mechanism.
Even if it’s trickier than that, there are probably lots of ways to selectively restore the epigenetic information in specific patterns or specific sites that might help chip away at disease.