As we know, 10k+ users can see deleted posts and vote for their undeletion. And, anybody can see his own deleted posts, and over some reputation (s)he also have a vote to un-delete it.
Except posts deleted by a diamond moderator. They can be undeleted only by a mod:
I have a purely theoretical question from pure curiosity.
What happens, if the deleting mod is later de-modded? Will the posts (s)he deleted become undeletable again?
P.s. the possible dupe is about the other direction (essentially: do the posts deleted by mod before he got the diamond is made un-undeletable retroactively). Although probably both depend on the same - missing or existing - feature of the SE software,
- It is clear only from a programmer viewpoint.
- We don't know the internals of the SE software, maybe they are handled differently.
- I think, this direction is much more important/interesting, because it could make posts public again, which shouldn't be ever publicized.
On these reasons, I don't think the other question would be an answer.
Next to these: The answers there contain only opinions, which are agreeable probably for everybody, but don't contain real information about this possibility.