Huh. Well that is... more trivia about Shadow/Assassin tanking than I ever thought I'd learn, haha.
But he was trying to DPS and wasn't even spec'd into Harnessed Shadows (not joking, because I got bored with the incredibly long kill times and started watching his buffs every time he Project'd; I never even saw 1 stack of the HS icon). Instead he was just religiously avoiding melee range and TK Throw'ing on cooldown.
It was like a Sage trapped in a Shadow's body.
I assumed he was tanking as that was the tank stance. It can be used as a dps decently but then you definitely want to be in melee and use double strike.
To the other guys: the trashless rotation was optimal and I know all that, I just didn't want to spam the thread with shadow stuff where it doesn't belong.
That said, the damage done by saber strike is minimal and doesn't really contribute much to threat gen and it doesn't do anything at all for mitigation. Double strike had its uses but before 2.0 it was a scarcely used filler, while now it's an integral part of the rotation.