Only if he'd say it to lionhearted in person, over a dinner conversation, per the HN etiquette guide. He's certainly within his rights to feel strongly about this, and to convey his belief in the harm caused by the demanding, uncompromising style of child-rearing; but there should be a way to do that with a modicum of tact.
I did not see the original format, but I have seen "You know what, fuck you!" said over the dinner table in such a situation. A short expletive is IMO appropriate for denoting intense emotional reaction.
It would seem odd if someone said "wow, this hurts would you mind backing your car off my leg" to the point where you might wonder if you had actually driven over them. However, "Back your @#%$ car off my #%^@&^ leg is less ambiguous". So, if your having dinner with the queen it's probably not appropriate but "I was deeply hurt by their actions" is somewhat emotionally ambiguous.
