Looking for a rule - No defense on robots without tubes

[Madison]

Originally Posted by KTorak

Although it isn't explicitly stated as a rule, I agree with it. It allows the intent of the game to occur, which in this game, is to score ringers on the rack and to strategically place spoilers over the opposing alliances ringers.

How do you know that is the intent?

The most you can infer the intent to be, above all else, is to score more points than your opponents using the methods described in the rule book. That's it.