Reread my post. Not at all what I was saying. He could have easily handled it much better. A simple statement like, "if you are going to act like this, we will be taking our present back," would have been ideal, or take the sister aside and tell her that if the niece doesn't apologize she won't be getting the present. But I would much rather the issue get addressed in some fashion, even if it is in a shockingly extreme manner, than just get ignored and swept under the rug. Better wounds from a friend (or uncle in this case) than kisses from an enemy. I honestly believe it was better that the uncle do this than do nothing...but, of course, there are a million other options and many of them would have likely been a better solution.
Also, I'm glad your father is a good example. I hope my children say the same as they get older. I try to live my faith first and home, then outside of it. Too many ministers do things the other way around and lose their kids in the fight for others. But it is hardest to live it day in and day out and in the moments when you let your guard down.