No, because people don't think like SSL libraries and there's a big difference between "you should trust this key" and "this key provides good enough evidence of authenticity to count as incriminating". To defeat the latter the key must be published.
Yeah, that simply won’t happen with keys in HSMs, where private keys reside more and more frequently nowadays, as they should for security reasons. They are specifically designed to make it impossible for the key to leak. In Europe for example, this is a prerequisite for signatures with legal value.
Which is fine if you don't want deniability, and probably desirable for legal signatures. But that doesn't make it something with no value. Parent poster was claiming it made no sense to want authenticity and then publish the keys. I'm just pointing out that there is a desirable property which uses that approach. And HSMs can be (and commonly are) configured to store keys which can leave the device, though setting a specific time lock is not something I think many support.
