It seems your proclaimed knowledge of the PK scrolls is incorrect dear
friend. Directly from the scrolls and rules:
If the DEFENDER is truly qualified (witnessed the attack, and;friend,
affiliated, or explicitly invited), the attacker has all
rights on this DEFENDER except for issuing. If the friend DEFENDS
and kills the attacker, then the attacker has cause, two kills.

In short Defending does indeed grant cause to the one you attack, they
just do not have the right to issue for it. Sorry to put a damper on the
rather lengthy post you wrote up, but I just felt the facts needed to be
cleared up.

Jago Verasall

Penned by my hand on the 23rd of Chronos, in the year 395 AF.