At least they didn’t sue her for the bad review?
Patrolling social media is not that hard, and it’s hard to fault a company for defending their brand. When you post to twitter, you do not have a reasonable expectation of privacy.
Also, and I stand to be corrected on this, the company that makes MoonPies is still an independent business (i.e. not owned by a massive agro/food products conglomerate). So it’s not a case of megacorp crushing a little person for a perceived slight.