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.
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.
Somewhat related link from quick googling:
https://www.sciencedirect.com/science/article/pii/S002192582...