No offense, but you are going off on a theoretical tangent that is barely on topic.
I’m interested in the stage/performance context and MIDI clock, not Caesium clocks, not USB.
MIDI is serial too as you know, but it generally avoids the packet issues of USB. So is that protocol getting the atomic clock data to your clock instance. Let’s forget about that, as that discussion does not actually solve any sync problems.
I agree with your last statement, which, had you made it in the post i previously replied to, would have made my reply redundant.