This question already has an answer here:
The way I understand it, when a user's account is deleted, so are all his posts that have a negative score (see #8 here). This makes a lot of sense to me on a main site. But as we know on meta voting means something different than on main, and a negatively voted post can still be worth keeping around as an important part of the discussion. (I'm sure some of the longtime users can point to a number of good examples where a negatively voted meta post was accepted, implemented, or at least heavily discussed.)
My feature request is that negatively voted posts of deleted users not get deleted on meta only.