I've never heard anyone saying crouch glitching is allowed, crouch glitching is point blank against rules, nothing else to say about it. Crouching alone might not be unlawful, but the real edgy thing is crouching and shooting, without glitching it, or crouching to hide behind a car or a wall then getting up and shooting.
EDIT: this is just my perception, not the whole staff view about it.