No reward/item, the guy says it just so...
a. you have your guard down.
b. he can get close enough to attack you.
I don't think so. Not the way the dialog unfolds. He blatantly tells you he's going to try to kill you, so what would be the point of such subterfuge?
I basically made this thread to make sure I didn't miss anything personally. If there is genuinely no way to get your reward I see it as a bug or oversight.
It's not the first time I've seen something like this. I actually wonder if Bioware intended for your choices in quests to reward you in different ways, but dropped that feature in favor of balance (so that people didn't feel like they "had" to make a certain choice for the best rewards) and didn't / weren't able to change the dialog to reflect that.
For example, in the Korriban series for Sith Warrior, you have to judge prisoners. Later, the overseer judges your performance. If you do all 3 exactly the way he would want, he says something like "A perfect performance, I think that deserves a special reward," but the reward for the quest is exactly the same.
That one seems more likely than Laying Waste to be just "flavor" text and the "Special" reward is just the reward you get for the quest anyway, but still... I can't think of any more specific examples, but I feel like it's fairly frequent that someone claims to be giving me something that I never receive.
If they really did once have and then removed the ability to receive special rewards from certain choices, that's disappointing, but I understand I suppose.