As soon as you spot a horribly designed outpost, whether it be a killbox, an exploited map (the lil box guy won't move/gets killed instantly,) or overall just an obnoxious series of long winding corridors or claw spamming, just abandon the outpost. You don't lose anything for this whatsoever, it's literally free.

Block the user on the first results screen. This stops their outposts from ever showing up on your map again and they don't even get the joy of watching you abandon their awful level design.

Save yourself the time and patience. Just block these people and when their outposts get literally 0 plays in the time it's active, they'll learn to make more interesting levels. If you feel targeted by this guide, we in the business call that a skill issue.