Gangplank Ult should not trigger Thunderlords Decree.

Well i noticed this the other day and i feel that if his ult is capable of dealing 150 damage per wave of 3 at first rank it gives people a chance to be able to get out of it within the first set. But nope once that last hit registers thunderlords goes off and deals an additional 80-100 damage depending of his level and you're MR. It lets a GP secure a kill on any somewhat lol hp enemy champ. Which i find to be unfair gameplay. I understand how constant AOE abilities trigger thunderlords, like morgana w, but for her it is only in the area around her. I find a great way to balance GP early game pressure would to code his ult so i would not trigger thunderlords.