First, there is no survival analysis. How is the mouse younger if it doesn't live longer? Similarly, the OSK "rejuvenated" mice display lower lean muscle mass.
Second, the causality is (willfully?) misinterpreted. The endonuclease used to causes DNA double-strand breaks does NOT directly alter the epigenome. Instead, it induces DNA-damage repair stress. One consequence, of many, is epigenetic (chromatin) dysregulation. DNA damage stress is well known to accelerate aging phenotypes. In fact, David published on how p53 stress from repeated DNA damage - using the same endonuclease setup - initiates a DNA damage response in turn promoting cell-cycle exit and cell elimination [0].
Third, cutting "non-coding" DNA in this case involves cutting specific ribosomes (cell translation machinery). Given that this pressure is constitutive, it's likely that these ribosomes evolve resistance to the nuclease by mutating functional sequences. However, the authors never assessed the mutation and function of these ribosomes.
Lastly, the in vivo AAV transduction efficiency isn't measured. This makes the OSK "rejuvenation" result hard to interpret. All cells get DNA damage (germline edit), but only transduced cells (<10% at best in whole organism) get some OSK exposure. Yet, the whole organism is "rejuvenated"? Is there a positive spill-over from OSK expression?
All the core claims about epigenetic information are either incorrect or grossly misleading. The perturbation, site-specific DNA damage, does not cause only loss of whole-cell epigenetic information. Hard to imagine how this got into Cell. I guess a big name and 20+ figures is all you need these days?