...IF the article is accurate, the man should not have fired a warning shot in the direction of the kids, and IMO should not have fired a warning shot at all. Should not have used pepper spray either.
1st rule of gun safety: always keep the gun pointed in a safe direction
Now... if the article is inaccurate, and the man feared for his life or the life of another, then the escalation of force applied (pepper spray first, then shotgun) becomes more debatable...
I don't put a lot of faith in accurate reporting when it comes to possible self defense situations