Man arrested for defense of home and self

A Long Island man was arrested for using a legally owned rifle to scare off a gang of thugs that were threatening him and his family.
His rifle was referred to as an AK-47, which is obviously a falsehood as that label only applies to the fully automatic version of the Kalashnikov design rifle.
His story is that he was about to drive a relative home when gang members accosted them and threatened them.
He believed them to be members of MS 13.
He grabbed his legal rifle and told them to leave.
They dared him to use it and stated they would kill him and his family.
More of the gang showed up because of the ruckus, raising the threat level.
He fired into the grass in front of them and they left.
He is being charged with felony reckless endangerment, which would require prosecutors to prove there was a good chance that someone could have been hurt, which they will fail to prove in court.
Whatever happened to "being in fear for your life" being a valid reason for warning shots?
If 20 men are threatening to kill you and your family, isn't that enough?
What was he going to do? Kung Fu them?