If there’s a “Search upvotes? with an “upvotes only” and “no upvotes” option in the advanced search, wouldn’t having “Search downvotes?” with “downvotes only” and “no downvotes” be much the same kind of thing?
I personally would find that very useful. If you simply searched one of the main tags (safe, grimdark, explicit, etc.) and selected “no downvotes”, you could create a browsing session that omits those images.
I believe the mods mentioned a while ago that they would never implement a “search downvotes” because they didn’t want people having easy access to things they could rage at.