Kelleran Beq cannot be defeated if his max health is reduced to 1 in TW

If Kelleran's max health is reduced to 1 hp via a mechanic like Shatterpoint, he cannot be defeated. I'm unsure if this interaction is due to the savior clause in his The Sabered Hand unique bugging, or the "cannot be defeated" clause of his By the Will of the Council leadership omicron. See example below.