There's one graph without an axis label and while it'd help give some context, the point is to show peak muscle and how it declines over time. The same point is shown in more detail on a graph with axis labels a little more down. This article is largely a very brief summarization of a topic from Peter Attia's book Outlive which is worth checking out.
The main theme of the blog post is taken from Peter Attia's "Outlive" book which is a compilation of science backed ways to improve health and wellbeing long-term which includes resistance training. Peter is very science driven and worth checking out. No "bro-y" at all.