That rule was changed by a proposal from Tony F in the last rule cycle (I voted against it as I thought it was too vague)

6.6: Knife-edge wings are not allowed. Leading edges must have two (2) millimeters minimum radius.

Change to:

6.6: Knife-edge wings are not allowed.

Intent:
In 34 years of competing in pattern I have never seen the minimum leading edge rule enforced. It is unnecessary for this to be in the rulebook.

The intent of this proposal is to simplify the rulebook and eliminate unnecessary wording.

Proposal passed 9-2