I think there are a couple of things that make Hook’s comment particularly jarring.
– Hook sarcastically calls the story about Snow and Charming trying to deal — however ineffectually — with abandoning their son a “riveting tale”. However silly that plot line about the haunting, I actually feel for the two dummies (maybe because I’m a parent myself).
– The hierarchy of it — Henry is a kid, and NOT Hook’s child. He shouldn’t be disciplining him, period, especially not over something like this. Add to this that Henry is clearly freaked out by this weird thing happening to him, and Hook comes across like even more of an egotistical jerk.
More generally, that scene to me felt really striking because Hook just felt like someone with the emotional sensitivity and intellectual maturity of a frat boy.