A few developments:
The manager of the restaurant had an interview where they point out that one of the reasons confronted Sanders and asked her to leave was the Trump administration's treatment of the LGBT community. (This was one of the first things that he talked to his staff about.) The family separation policy was also an issue.
And Trump has gone on the offensive, tweeting:
The Red Hen Restaurant should focus more on cleaning its filthy canopies, doors and windows (badly needs a paint job), rather than refusing to serve a fine person like Sarah Huckabee Sanders.
First of all, remember, when he calls Sanders a 'fine person', he also used the term 'fine' to refer to neo-nazis at the Charlottesville rally.
Secondly, curious that Sanders would want to eat there if the restaurant was really in such a bad condition.
Lastly, I wonder of the owner of the restaurant would have a cause to sue Trump over his comments. After all, Trump does have a relatively visible forum that he's using to criticize the restaurant (a place that Trump has likely never visited). And his twitter account is often used for official announcements, so the store owner might be able to claim "the government" is targeting him.
https://www.ctvnews.ca/world/trump-trash-talks-restaurant-that-booted-sanders-1.3987410