IMO some other calculation should be used as it's impossible to use as intended since if the armour is broken, why not just CC the guy? Taunt should serve as a tool that can be used to protect everyone else from the guy who you can't break yet but since the status is blocked by armour, can't be used this way.
My proposal for the skill to fix this situation is instead of making it a debuff, make it a buff based on the characters armour. Enemies within taunts AoE can't leave the AoE until the taunting characters armour is broken.
