It's not so much even "rogue" moderators. It's just regular moderators doing their regular moderating. If they don't know that marking the report complete stops the admin from seeing it, then they'll ban the problem user from the community, and remove the post, and think that they're doing the right thing, but they have in fact, stopped the admin from seeing the report and banning them outright.
Ah okay that's less problematic. But could it still cause problems if a rogue moderator decides to be trouble for the instance admins?
It's not so much even "rogue" moderators. It's just regular moderators doing their regular moderating. If they don't know that marking the report complete stops the admin from seeing it, then they'll ban the problem user from the community, and remove the post, and think that they're doing the right thing, but they have in fact, stopped the admin from seeing the report and banning them outright.