I think his post is fantastic. It accurately reflects the true nature of aging. In our 20s it's easy to adopt a motto of austerity. Backpack across Europe staying in hostels, crash on a friend's couch for a week, drive across the country without A/C, etc. In our 30s we start to soften. Mental and physical discomfort become less tolerable and it is a fight to keep that rubberband stretched out. I feel this keenly now, about to turn 39, and trying to figure out how to keep my nomadic travel lifestyle alive while realizing there are certain things my wife and I just won't tolerate anymore. MMM is now in his mid-40s. Age is constantly going to be putting pressure on that tolerance rubberband to tighten up and he is succumbing to that just a little bit. And that's awesome, because he is modeling exactly what happens to everyone else. I understand a new reader might not realize that but he does point out that he's older.
If you become a multi-millionaire and at 45 you're still willing scrimp on some once yearly travel comforts to save $1,000 then you are truly a badass. You've kept your rubberband stretched more than basically anyone else. But I think it's good that his post shows that we will naturally soften in our older age, because it's the truth, and something worth thinking about for those considering FIRE while young.