Pretty much this. I think it started with a tossed-off “oh, haha, I always imagined he was a bit gay!” comment which, Harry Potter fans being as fervent as they are, became a much bigger deal than she anticipated. So then she gave the fans a bit of context by saying “well, he was in a relationship with his best friend who became evil, which is why he’s celibate.” None of that would matter to his character as we see it in the movies, except that now they’re literally going to film that chunk of his life, so avoiding that supposedly formative relationship is going to be kind of awkward.
