Based solely off the trailer I can see how a big American storefront would err on the side of caution here. There is very little to gain from carrying a game decidedly built with controversy in mind, but a lot to loose.
With the publicity around it and sales still possible through alternative stores maybe things will turn out alright for the developer in the end. "Banned" media is always in demand, after all.
Valve is pretty upfront about being a business first and foremost. Their customers are loyal because they consistently provide high value at reasonable prices, even though they are in a dominating position in the market. They've taken unpopular decisions in the past, but never any that seriously alienated a meaningful chunk of their customer base.