[Mastonevich]

Strategies aimed at and/or game play resulting in the damage, destruction or inhibition of opponent ROBOTS via actions such as high-speed or repeated, aggressive ramming, attachment,damage, tipping, or entanglement of ROBOTS are not allowed.

Inhibition is such a broad term:

All references from dictionary.com

inhibition
1. the act of inhibiting.

inhibiting
1. to restrain, hinder, arrest, or check (an action, impulse, etc.).

hinder
1. to cause delay, interruption, or difficulty in; hamper; impede: The storm hindered our progress.
2. to prevent from doing, acting, or happening; stop: to hinder a man from committing a crime.

I think the important part comes in the terms:
high-speed or repeated, aggressive ramming

You can play defense, just no use of high speed, or repeated aggressive ramming the way I read it.

Godspeed to the referees!