Would it make any difference if the girl instead of saying no, said instead, please don't, please stop? Or would it still be wrong?
I think we're focusing on the wrong part of the encounter. What matters is: if the girl is on property owned or managed by the man, then she doesn't have the right (crap, finity, I read your post, but I still don't get when to use 'r' or 'R') to decline his request for sex.
"She came over to my place. I asked her for sex, but she politely declined. Obviously, 'my house, my rules' came into play, and since she didn't leave on her own, I had the right to use force to compel her to have sex with me."
That seems to be the most analogous to the situation in the OP. And I think we can all agree that the girl would NOT be required to leave in order to avoid being forced to do something she didn't want to do—something she couldn't be convinced by reason to do.
No idea what state that site is referring to but it sure as heck isn't IN. I'm sure of that because of the minor and alcohol reference. If I take my 16 year old out for their birthday, it is illegal for me to order them a glass of wine, or to let them have one in my house. The site says it's okay.
Oh, I didn't know that! I guess it's been a while since I was under 18 and since I don't have kids, I've never really tried to figure that out. In case anybody is interested in the official record, it is in IC 7.1-5-7 sections 9-11.