Hey there
As one of the main tanks and Raid Leader of my guild, I have encountered this "problem" every time since our dps got "too high" for this bossfight. It's not really a problem, you already stated you are aware of having the debuff, which is the first step, second is standing there looking like an idiot doing nothing for 6-10 seconds. U should be fine during this phase because your taunt lasts 6 seconds, and incase you do lose him, u have your backup aoe taunt ready.
Hope this helps, if you have any further questions feel free to pm me, might not keep track of this thread.
-SnipeAlott