They have to decide whether American buyers will buy it in sufficient volume to justify it. Remember, it's not just selling the car...they also have to service it, which means additional training for the techs, plus stocking parts. It's already annoying how few parts dealers stock anymore. Although I have zero experience with Chevy dealers in this regard, I'm highly annoyed with my previous experiences at Mazda and Honda dealers. Pretty much anything beyond fluids, filters, or windshield wipers is a special order item and takes 3-5 days to arrive.
There's the cost of going through U.S. EPA and NHTSA certification.
There's also the cost of adequately marketing the car.
I'll keep going...there's the concern that people who buy it might otherwise have bought an existing model (like the Equinox). They don't want to compete against themselves.
But wait! There's more! If they DO sell it here, will dealers have enough space on the lot to provide a decent selection? Providing a good selection of Orlando models means less selection of other Chevy models--there's only so much space on dealer lots.
It's a non-trivial decision.