I think it's crucial to point out, though, that Eugen Rochko's motives for stepping down were explicitly personal. He's still quite young, Mastodon itself is still quite young, less than a decade old, and Rochko could have continued in his position for some time. He stepped down because he wanted to step down, not for some selfless reason like succession planning. And I'm not criticizing Rochko for that; he can live his life the way he chooses and do what makes him happy, avoid what he finds unpleasant. And he's to be commended for the mentioned peaceful transition of power. However, there's no inherent reason why Matt Mullenweg or DHH should step down just because Rochko stepped down; their personal goals are obviously different. And Rochko behaved very differently while he was still leading Mastodon.
The author clearly wants those other leaders to step down because he doesn't like those leaders and how they behave, not because of some abstract idea of succession planning. I don't think the metaphor of a king's death is apt here, because nobody has died or become incapacitated. They've just become overtly contemptible.