Well, that's true. All countries have to look out for their own best interests, and they will not always coincide with ours.
However, the fact that this particular country (UAE) officially subscribes to an ideology which is radically opposed to us, and in fact is seeking our death throughout its sphere of influence, means that they perhaps should expect to have to provide a little more reassurance. I think many people probably recall the way Turkey bailed on us at the last minute, when we were relying on it.
As I say, I was not automatically opposed to the deal, and I think it should have been examined. (Of course, once I found out that Bill Clinton was heavily involved in it, I will admit that my suspicion level went up.)
Officially? What officially? Show me. Provide a link to an official UAE statement of their radical ideological opposition.