I think a great heuristic here is this: your customers can be publicly negative, but you cannot.
If you publicly flame a customer then, no matter how deserving the customer was, some future potential customers will look at that and say "That could be me." Most businesses, I think, can't afford to risk that.
There are some notable counterexamples, in my opinion they are the exceptions which prove the rule, i.e. when the business wants to fire the customer and make an example of him/her for others.
The best example of this is the Drafthouse movie theater in Austin, who created a great PSA wherein they ridicule a customer for insisting she had the right to use her cell phone during a movie: http://adland.tv/content/drafthouse-movie-theatre-makes-keep...
I agree 100%, the tweets are not helpful, but I disagree with the "disgusting" description and felt it was a little over the top.