I'm perfectly willing to believe it. From an Occam's razor perspective, exercise most directly and clearly is wear and tear. Stories about how the body overcome and benefits from that are more complicated, hence more likely wrong.
By definition, there is a point in between which maximises longevity on average. This may not be the same as the point which maximises quality of life.
How exactly does exercise "damage all your parts"? You need proof to back up that bizarre claim. Humans are evolutionarily designed to be long distance athletes.
Both processes have both short term and long term cost and accelerate senescence. More cells need more replacing under normal circumstances and this is limited by your genes. The absolute number of cells that will ever get replaced in your muscles is strictly limited in what is probably a measure against cancer. So increasing strength in muscles brings the day you get cancer forward. Not by much.
To a point this can be a worthwhile trade off, as it improves other aspects of your body.
But if you need or use food additives, or, god help you, steroids, you're far past that point.
In the short term over exerting muscles releases toxins, and over taxes your liver, heart, sometimes lungs, pancreas, and more. Needless to say this can trigger problems, and cause cell death in those organs too.
And lastly physically stressing your body can and will of course damage it. Even when there aren't large scale injuries there is damage. Any exercise will cause blood vessel ruptures. Will cause cell deaths due to crushing. It will bend or reshape your bones. Minimally, but nonzero. Of course, having a bmi of 35 will do cause more of this stress.
How is a process of building muscle through exercise, which humans have been doing for hundreds of years, and which is extremely well understood by modern science more likely wrong than a bizarre metaphorical similarity to how physical objects degrade due to stress? Use it or lose it is our latest understanding of both the mind and the body.
However, the article just says minimum exercise should be maintained for minimum entropy... there's no analysis as to why minimum entropy is a good thing. Longevity and wellbeing are complicated, multifactorial goals, and are certainly not determined by something as reductive as "biological entropy".