After some searching around, there doesn't seem to be any new information on this subject from the creators of Once Upon A Time. It is possible that they simply wanted to avoid giving attention to the issue.
It is true that, at one point, writer Adam Horowitz said it was not rape:
she didn't use his heart for that. I know. Trust me.
However, Horowitz has also contradicted that, saying instead that Regina did rape Graham:
@MdMeiriona: So, once again I'm going to ask. When are you going to stop joking and address the fact Regina raped Graham.
@AdamHorowitzLA: She also killed him, which we addressed. Neither thing's a joke. Regina has done terrible things which is why she is the Evil Queen.
Notice that Horowitz says "also", as in "in addition to". In other words, he's saying, "In addition to raping him, she also killed him; she is evil."
@Jonah makes some good points in his comment.
She erased his memories and added new ones to make him into her lover. That was nonconsensual, thus rape. (...) Had Graham managed to survive long enough to see the curse broken, he certainly would have disagreed [with her actions].
It should also be pointed out that, in the farytale world, the evil queen did rape the huntsman.
From a Once Upon A Time forum post:
On the other hand, the Huntsman was most definitely raped. The Queen took his heart, then kissed him, then said she could kill him at any time, and that he was now her pet, and asked for him to be sent to his chambers. Since it was doing it or dying, it's definitely rape, as the definition includes coercion.
Unless someone gets the creators of Once Upon A Time to shed new light on this issue, this is probably the only answer you're going to get.