Peter Ansell wrote:
If they leave because a userspace page, which was not promoting collaboration on wikipedia articles, was deleted then they were *not valuable* to the encyclopedia.
That seems like an extremely petty criterion of "value." Have you checked the contributions lists of the Bathrobe Cabal members? If all they do is work on the Bathrobe Cabal page, sure, no big loss. But considering they have to run the gauntlet of RfA to join the Bathrobe Cabal that seems unlikely. Almost by definition they've had to contribute a lot of valuable work to Wikipedia to get there.
It could however be affected if others figure out that admins aren't consistent and chuck a fuss because their Userspace pages were deleted for the same reason that page was kept in a shortened discussion.
We could leave all harmless user subpages like this one alone, admin-created or not. That would be a consistent approach.