This might be not a feature in the way you would have thought but the map might need some improvements/bug fixes
Unfortunately Protons map has some spots where the AIs logic will break so that you can easily farm them which is against the intention of this mode:

- The area directly between church and castle wall. Standing there will make most horde bots become passive
-> moving the church a bit more backwards so that those spots wont be accessible should fix it
- between toilet and church. Same as above
-> deleting the fence and the toilet should fix that
- the area behind the castle barn (in which you can buy 400hp upgrade)
the blocking volume which should prevent you from jumping on top of the barn is misplaced (you can still stand on the roof at the sides)
-> moving the barn to the wall (so you can not run behind it) or further away and placing a railing at the stairway should fix those map bugs