Of course, it COULD be bad. Real bad. Hand-waving away such concerns is irresponsible. Having a major oil source friendly to an often hostile nation could have real, even deadly drawbacks.
But so too does always turning a blind eye. If we had gotten into this relationship and worked to reduce the threat (such as investing in other energy sources) we'd be in a better position, we could be at a point to change the relationship at reduced risk. We didn't, and we need to face the concrete realities we're supporting out of fear of hypotheticals.
Because now we may be safer, but we're supporting what we proclaim to be against. When we wield moral superiority, it's undercut. When we tell our children to be patriotic, we know the legacy we're leaving them.