It's a personal attack, but not actually an ad hominem attack. There is a difference between "McDonalds has a bad business model because their burgers are gross" and "McDonalds is unpleasant to eat at because their burgers are gross." The poster's attack is of the second form.
Still fallacious. To continue your analogy, this is like saying that all McDonald's stores have unpleasant food because of that one store. Yes, something should be done if it wasn't a one time thing, but no that does not mean the other stores necessarily have the issue(although they could).
