I didn't look at the comments, but it was an interesting letter, though the response was pretty banal.
Abhorrent actually seems like the wrong word to me because it almost implies a sort of moral problem, and it seems like that is not what she meant. More like dominating him in that way was just a really significant turn off for her. I didn't get the impression she had a problem with him having these desires, she just was really not interested herself. Perhaps if she'd used slightly different language people would not have picked up on that element.
The other thing that struck me was that this wasn't about just a man insisting on kink - the women also seems to have wanted him to participate in her kinks. My guess is if he weren't keen she'd not have pressed it, but I think there is something in this idea that in a modern sexual relationships you'll each have your kinks that are part of how you get off and you have to try and work that out somehow with your partner. It kind of sets the stage for these sorts of issues.
It all seems like a lot of work and weight for relationships to carry for me. It's difficult enough to meet someone you like, share values with, find attractive, and want to have a shared lifestyle. Having to match up your kinks developed over years of varies experiences seems like a major pain.