Ice cream has a legal definition in the US, and it doesn’t require cream as an ingredient.

>Ice cream shall contain at least 1.6 pounds of total solids to the gallon, weigh not less than 4.5 pounds to the gallon, and contain not less than 20 percent total milk solids, constitued of not less than 10 percent milkfat. In no case shall the content of milk solids not fat be less than 6 percent. Whey shall not, by weight, be more than 25 percent of the milk solids not fat.

Whether McDonald’s product meets that standard, I am not sure.