My understanding is (and I’m open to correction) that the term organic typically refers to the source of the food, not to the treatment of it (of course, assuming that you don’t add non-organic products in treatment). So there are things like organic potato chips which are organic potatoes, cooked with only organic ingredients.
Pasturization is, in essence, a cooking method. It doesn’t add chemicals to the milk. Given that commercially distributed milk pretty much has to be pasturized, places like Whole Foods wouldn’t be able to sell organic milk if pasturization made it non-organic.
BTW – when I was in college in Western Mass we used to buy our milk from a farm next to campus. Unpasturized, unhomogenized, straight from the mixing tank. I really miss that.