For how I saw the idea of Ian needing to be more bold/kinky/experienced to keep Ivy's interest, you're right, it wouldn't stop them from having sex now/soon, but it would potentially take away from the build up and Ian presenting Ivy a challenge from the start. It also feels too much like 'barely an acquaintance' right now to justify Ivy being interested in Ian to that degree - at least that was the impression I got last time I played. Maybe I'm misremembering?
It wasn't about the dominating so much as it is about Ian going out of his comfort zone as 'regular old Ian' and becoming more daring. Basically becoming bold enough sexually that he could match Ivy, and more then just satisfying her, leave her wanting more, and not having be just another guy she can easily move on from.
Also, not being "put into a position to be dominated" is kinda irrelevant, seeing as getting caught up in the moment during sex between two kinky people can pretty easily lead to D/S when they're both vying for control and getting lost in the moment. That's kinda the point - if it were up to Ivy she'd likely retain control indefinitely, but Ian has to turn the tables on her in and out of the bedroom if he wants to be the exception to her idea that 'men are easy to manipulate'.