Wagtail
Horse servant
I think that H sounds like a man not fully in control. I would leave the yard as no, I would not trust someone like that around my dogs or horses. The fact that he has happily play fought with the dog on other occasions, yet saw fit to react in such an extreme manner on this occasion does not sound like a stable personality to me. Whether or not a dog should be allowed to play fight is irrelevant as 'H' quite clearly accepted and encouraged this behaviour and therefore condoned it. Then acted in a totally unpredictable and violent way.