In how many states would the police arrest the Samaritan for brandishing?
Realistically? Maybe three. Hawaii, New Jersey, and Maryland.
In Hawaii and New Jersey, there are almost no carry permits issued.
In Maryland, if he was in Baltimore, it might happen. It is pretty hard to get a permit in Maryland, and the city government is insane.
Much depends on the local government. The vast majority of local governments are going to side with the armed Samaritan who stopped a "hate crime" against visiting Jews.