There is a scenario where the "remove" action in <RepositoryUpdate> block becomes unusable:

1) new repo is created, and root repo adds the new repos using the "add" action
2) client does an update, and the new repo is added to the list in maintenance tool
3) the new repo is removed, and "remove" action is added to root repo
4) client does an update, but fails because the new repo (that is now removed) is in the list before the root repo, so the "remove" action does not take affect.