I just tried to find a recent answer I wrote (or comment, can't remember), but I couldn't. I assume the question was deleted. Can the deleted:1 operator be enabled to 10k users? We can see deleted posts, so why can't we at least target them in search?

I understand that allowing us to search for all deleted posts from someone else can be problematic. Quoting Yannis Rizos' comments:

if deleted:1 becomes available to 10K+ users there should be a restriction on coupling it with a user id (except perhaps when you are searching for your own deleted posts).

So, user:<userID> deleted:1 would be disallowed (except for your own user id), but something like [tag] deleted:1 would be allowed.