Just skimmed it.

I think he's right but he's talking about something different than the
couplings faces being true and square to the shaft. If you have a
true running shaft pulled out of line by the engine moving on the
mounts or not being perfectly aimed towards the strut, that's one
thing and probably not a big issues as he says. If the engine is
trying to wave the far end of the shaft in a circle under the same
circumstances, I think you are going to have some noise.

--

Roger Long