Probably not. Which is sort of the point on this thing: if she didn't do it, someone else would. And hey, guess what: she's not a saint.
But who cares?
She could never be so awful that you'd think: "Gee, I wish Walmart could have got to use "Let's Roll!" without paying someone" ... because, really (as Doug has said): it's none of your goddamned business.
I applaud anyone who gets Walmart to write them a check, even for something as stupid as her husband's last words.