Could be. But also, ice cream manufacturers buy their ingredients more cheaply than consumers do. It is very possible that the cost of milk/butter/sugar at Walmart reflect Walmart deciding to lower their profit margins on these items, even if the cost to Walmart has increased.

Or - Walmart is a big enough supplier that they have stable contracts with manufacturers, and are able to purchase their ingredients for the same cost as always, while Turkey Hill et al is competing over what's left. (Like Apple, buying up TSMC runs.)