There's no way for code to magically understand what you want and exactly how to do it.
If you have an area of bricks you'll need some sort of flag that makes them different than any other bricks you don't want bots to spawn on.
either a specific name, a seperate brickgroup, a designated position, anything
however, just having code figure out that a 2x4 at one place can spawn bots but a 4x6 at another place can't, isn't going to happen.