Saying you have an OT for trash so TC isn't as important is ignoring the damage mitigation of TC which is arguably much more important on serious content than the threat generated by it. The slowing effect is huge.
All-in-all I think it's a great gimmick spec if you're tanking content that you vastly overgear or is poorly balanced, but on progession content it's not going to get you very far.
I mean, at the end of the day, what's the point of "insanely" high threat? Unless DPS are regularly catching you, there's no reason to go "insane" with it. Enough threat is enough and more doesn't get you anything except bragging rights among other tanks.
My question is, does this build put out significantly more DPS than one using sword & board and shield slamming for higher criticals more often? If not, I just don't even think it works as a gimmick spec honestly.