The intproc doesn't work as a tank. It states in the tooltip, that it's only active for healer roles.
Doesn't really decrease it's value though if you don't have the heroic thok trinket. Infact, if you get the heroic thok trinket I would just use both in most situations, the HC WF sha trinket is about 1100 mastery and 1600 haste for me atm + the crit bonus iirc.
Though I got a question - is there a problem with the arsenal atm? Because I'm at 21602 haste there but only at 21067 ingame. Or is that a problem with haste calculation with double AMP trinkets? o.O
Edit: Lol okay - if you want to go with two AMP trinkets you will have to equip the one with higher ilvl first and then the other, then you will get higher stats. Lolwut.