Ok, these are words, but again I'm not talking about DNS security here, I'm talking about SSH key distribution. Why would you elect to have your key distribution controlled by the DNS PKI? What's the upside? The downside is, an actor with control over the DNS PKI (there are many of those; see, for instance, every DOJ seizure of a domain) gets a degree of control over your SSH authorized keys. Seems... bad?

Agreed completely. The threat model for DNSSEC is vast; why would you diminish the security of a perfectly good end-to-end model in SSH keys or certificates, as long as you control 100% of that infrastructure.

Introducing any outside actors at all objectively diminishes the security of the whole model by becoming another link in the chain, even if that link isn't necessarily the weakest (and I certainly believe it would be, because both DNSSEC and the public Certificate Authority industry are object lessons for the abject failure of highly centralized global, government-wide, or even just company-wide security), but simply increasing any of the surface area is enough to decrease the security of the system.

You'd have to compromise not only the root keys just to get into my infrastructure, but sign all the zones from there downwards, and intercept all DNS traffic leaving that server in the first place. That's secure enough for me.