To be fair, he may not be aware of how those expressions appear, and they may not reflect as extreme an intention as they seem to. I remember watching back some video of when I was cat-herding my kids when they were about 4 and 8, together with a couple of their little friends. It had been frustrating, but not especially unusual or difficult, but I was horrified by the range of expressions on my face which were more like paroxysms of fury than anything else.
That said, he's got previous, and he's just behaved unbelievably badly to his Clarence House Staff.