Walmart cannot tell anyone to copy the software, lest that person become an agent of Walmart and violate the terms. So Walmart has to hope that some third party relicenses the software out of the goodness of their heart.

Of course, who knows what'd happen in court if that scenario was actually tested.

EDIT: if you are serious about that line that you'd extend them license, automate it! a little script that finds repos with that license and copies them to straight MIT would be pretty silly