For every story about Sam's 'ol red Ford' and him unloading trucks himself there is one about corporate schemes and shenanigans. "In Sam We Trust" does a nice job about explaining how Sam used Off Balance Sheet accounting and threats of litigation to grow into a nationwide company.
And before I get labeled an anti-business socialist - I have no problem with (most) of what he did. He acted (mostly) within the law and within contemporary social/business norms. Evaluating from the standards of the time, men like Sam Walton and Don Schneider are to be admired and emulated, but pretending they wouldn't/didn't take actions similar to this lawsuit is ludicrous.
I'm also on Walmart's side in their filing this lawsuit. If Walmart doesn't at least file this suit then they could get tied up for DECADES in civil class action lawsuits from property owners in the area about smoke remediation, hazmat cleanup, and health issues - some valid, most not.
Stepping back a second, let's think about how many times upper management has made a dumb as poop decision that rank and file KNOWS is a bad idea. Fire fighters are going to follow that command without hesitation, assuming command has more information than they do. IF the commander made a dumb call, a call that other commanders wouldn't, then Walmart should be shielded from some liability.