1000 AP is really not that much important for a tank. Tanks get 10% hp as AP from Vengeance, which means you end up with 15-20k AP from it alone easily. A 1000 more or less should not make a difference. Even though 250 armor is not much, it's still the best mitigation enchant for tanks at the moment, and avoidance and mitigation are the most important things for tanks at this point, since threat hardly matters anymore.
We do admit however that it deserves more than 0 points, we probably overlooked it because there are not many plate wearers who have tailoring. Thanks for reporting this.