This is text book retribution for a employees engaging in protected activity: one manager was dumb enough to say it out loud. Tgis kicked this issue out of the legal gray area Starbucks would love to occupy.

Think of it as firing a whistleblower for poor performance: it's never a good look and ought to impose a supersized burden of proof on the employer even in the rare cases where it's true.

There is no need to perform mental gymnastics when Occam's razor perfectly applies.