Well people don't just wake up one day and decide to brain wash their kid. You really have to piss off your father to endup like that.
If some noble were awfully resistant to marriage in ye olde days they'd be sent to an order and unofficially cut off inheritance in some way -- such as accusations in one's last wills, etc. Mindrape is something else, since filial piety goes both ways.
Dorian is also an entitled noble wuss whatboutist who believes knows what's best for everyone and sees paternal value in slavery. If he didn't have any faillings, then he'd be too perfect.
No, what I think is worth criticizing here is how much of an obvious gay conversion therapy parallel his story devolves into. As I said, there are quite a few other things that could have lead to the breaking point between Dorian and his father. Like his stance on Blood Magic itself.