I'm not sure why you think being born in Kuwait is relevant to him. That's the only connection Abdulazeez had to that country. He had Jordanian citizenship, and visited there a couple times. Not Kuwait.
A couple relevant points to be made. First, why do you guys seem to assume through implication that Abdulazeez was necessarily part of ISIS? Aside from the fact that investigators have found no link between him and any group, he could very well have been part of any terrorist group that wasn't ISIS. It's not like they're the only group in the area that could have gone for him. Next, he wasn't as devout as a Muslim as you would think. Sure, there's the blog post, but in light of other information, that seems to be at least partially an online persona. A few months ago, Abdulazeez was arrested for a DUI, and police, who noticed that he definitely was NOT sober, smelled alcohol and marijuana on him. This is not very devout in my mind. That's not even to go into the whole murdering innocents thing (during Ramadan, no less). Cast in this light, he is not as devout as everyone once believed. I assume the ire and cause of this attack had more to do with a political distaste of the United States and its military.