I got the idea of them portraying him as being heroic in forgiving Gwen from an interview one of them, probably Quesada, did after the fact. Marvel is just being clueless. They've said that the story adds depth to Gwen's character and makes Peter look noble, which is not what I got from the story at all.
I guess you're right in that it's not implausible that it could end up that way, but it does involve a lot of manipulating the characters into just the right position (bad choice of words here, I know). We didn't see any of the manipulation, so it looks like they're presenting it as just something that they naturally would have done. Honestly, my bigger problem is that she never said anything to Peter (while assuming that he'd help her raise the children)and acted as though nothing happened for months, maybe even years. Of course, that's because, as far as she knew, nothing had happened.
Now, if they HAD turned out to be Peter's children..., but that wouldn't have made any sense either.
Whoever retcons this is going to be the most popular Spider-Man writer in decades. (Better than the guy who gave Gwen Stacy illegitimate children with Norman Osborne and the guy who had Peter having blackouts and forgetting whether or not he had drunk sex with his roommate? There's something for the resume.)