Re: Moral Dilemma...
Confront him again telling him what his son said. See what he says.
Make public notifications ( however you want) of his business name and what he is doing. Lsit the facts only. No name calling.
Make separate posts on craigslist explaining what he is doing and ask for a boycott.
It probably won't go anywhere with Walmart, but you can keep going up the chain of command with them telling them that their employees are demonstrating poor business practices.
By the way, what walmart up there sells powder?
We don't see it down here.