> The problem with a gerontocracy is you have masses in cognitive and physical decline at the peaks of power.

Well... that's exactly what we have been able to observe in the US. Trump and Biden are horribly old, both have shown serious cognitive and physical decline with Trump definitely being the more serious issue (I never heard rumors about Biden crapping in a diaper, with Trump the rumors are so consistent they're practically a meme, and now we get to look at his very weird hand with no explanation why it's weird all the time). A bunch of Congresspeople died of old age in office, with the most prominent being Dianne Feinstein. The Supreme Court is even worse, with RBG being the most infamous for not stepping down and allowing Obama to nominate a successor, thus handing the post to Trump.

> Old people aren’t a problem, aged people in command are.

Both are a problem. Old people are vastly more likely to fall gravely ill at any given moment, they take longer to recover, and they take longer to learn new things (or refuse to do so outright). Aged people tend to entrench themselves in their position and fear getting replaced and losing their privileges, often thanks to toxic work ethics.