As a result of Mackey's letter, Whole Foods (already known for unethical union busting tactics) came under a lot of pressure from progressive groups. Many people have boycotted Whole Foods since his letter. And as a response to that campaign (or rather, as a pretend response to that campaign), the tea party called for a "buycott" of Whole Foods where they would start shopping there to support the CEO's "courageous" stance and, of course, "free speech" (unsurprisingly the same people who love Mackey's "free speech" recently called for a boycott of Build-a-Bear for acknowledging the scientific consensus that climate change exists, so it's hard to take their love of "free speech" too seriously).
The TPs exaggerated and manipulated their numbers to make it seem like their buycott made a big difference, and as a result they got a fair amount of media attention. And I wrote at the time that their campaign had absolutely no chance of actually helping Whole Foods, and furthermore that they didn't really care about helping Whole Foods since their only goal in this was to create a political stunt that allowed them to make a few extra anti-healthcare reform remarks to the local media.
I think this point has been validated recently. John Mackey is giving up the title of chairman of Whole Foods, specifically because of concerns that he's tarnished their image. Now it's true that he's still their CEO and on their board of directors, so no one who was boycotting should rush out to go shopping there, but this action still shows that his letter was unmistakably harmful to the company as the company is taking actions to make it look like they're punishing Mackey. If the "buycott" was successful, Whole Foods wouldn't be taking actions to punish Mackey or make it look like his role in the company is diminished; they would be putting him out front and center. But, as I said, the buycott was never about actually helping the company, and it never had any chance of significantly affecting the company, whereas the tarnished image of Whole Foods among liberals is unquestionably harming their bottom line.
Of course, the TPs don't care. This was just one of a long string of unprincipled publicity stunts for them, and if Whole Foods went out of business tomorrow, they wouldn't even bat an eye.