I think it should be pretty obvious why those posts were deleted. The fact that it's now a public thread is the very reason why they WERE deleted. Obviously they wouldn't need to be deleted if this was in a super or admin section.
I don't see in any way how it denigrates their past service.
Whats gained is letting the members know, and rightfully so, whats going on with staff etc. so they know who to report hackers to, who is on the current staff etc. This information should never be kept in the dark.
I also think it would be more of an embarrassment or annoyance to the demoted mod having to explain to the whole krew in shout every time a member goes
you're demoted? Why? What did you do. That would get old quick.