Border Sentry?

What's the deal with BorderSentry bots? There's a lot to like with the offering: a massive energy bonus, and starting against the walls rather than in the middle of the battlefield. Sure there are also significant downsides, but still, I'm surprised to see zero instances of it out in the wild. Is it not allowed to participate in the rumble?

The rumble rules were made long before BorderSentry bots.

I guess BorderSentry bots were introduced in a melee competition to nerf Corners-like and Walls-like strategies.

They were designed to act like house robots in robot wars. I am not sure if they generate a score. They were designed more to be challenges than challengers.

The API docs point out they can't generate score. They can't damage bots outside of their border area, either. However I have a feeling their bullets can still intercept other bullets whether or not they would have dealt damage, and in the 1-on-1 rumble bullet shielding is still pretty effective even without directly dealing damage. So hypothetically, a team comprised of mostly (but not entirely) bullet shielding border sentries has some potential.