My great grandfather, the one who lived to be over 100, was strong but short.  His son, who is now 93, is a little taller, lives a sendentary lifestyle, and does eat his share of omega 6 PUFAs (but hardly anything in the way of omega 3s).  He had a pacemaker put in nearly 20 years ago, has had hypertension for decades, and now has pain in his back and legs that can be severe.  I saw the mole rat story - Ray Peat pointed out that this animal has less oxygen available to it, which is of course necessary for oxidative stress.  Do you have a citation for it, so that I can see if it is the same story that I read?  If you look at the top killer "diseases" for humans, "heart disease" and cancer, and then look at the molecular-level mechanisms, you see that it's all about oxidized LDL (for heart disease) along with AA metabolites, in the vast majority of cases.

 

As to the muscle build up, you might want to think along the lines of cell stressors.  If cells are stressed, and there is "fuel," as well as the "building blocks" for new tissue available, there should be no "disease" in the young and healthy.  Ray Peat said something about testosterone and/or androgen having the potential to be helpful in this context, if I remember correctly.  Did you look on his site to see if he has anything on this subject?  He has more of a hormone and tissue understanding, whereas I find the molecular and cellular level to be easier to understand and more basic, at least in certain ways.