He certainly can. And then he can go to jail for breaking the law.
And since we're playing the "hypotheticals that conveniently make our point" game, let's rewind a bit...what if the person that was going to harm his family was also an ex-con, and was stopped for an expired brake tag on the way to murder Billy Ray and his family. Instead, thanks to the laws in place, he was arrested for having a gun in his possession and sent to jail. Billy Ray and all of his peeps are safe and sound tucked in bed, and another criminal is behind bars. Yay!