Actually walmart has a corporate history of trying to help the ordinary consumer.
 
Not for altruistic reasons obviously and the net effect of their business practices is certianly debatable whether or not it helps or hinders in the end, but you can see some of this in their recent efforts to provide low cost banking, pharmaceuticals and alternative insurance to their customers.   

If bitcoin can actually help lower income types I don't think it's unreasonable that they might try to incorporate something in their financial services.  Of course, bitcoin would have to be of real benefit to their customers and at the current time it isn't.