The movie is based on a real historical figure - Hypatia of Alexandria - and actual events surrounding her. But a lot of it is fictional, including the suggestion that Hypatia might have had inklings more than a millenium before Kepler that the planets moved around the sun in elliptical orbits.
But perhaps that is the point. For all we know, she could have been thinking those things, or might have one day, had she lived. And so the message, however much license it is taking with historical evidence, is that when a great thinker's life is cut short, we'll never know for certain what was lost as a result.
That's from: Exploring Our Matrix: Thoughts on Agora
The movie in question is called Agora.
The completely unwarranted move here could be mapped out like this. There is no evidence that N was about to make great discovery X but she might have been. That statement is equally true for any name N you might want to substitute. It's an absolutely vapid claim.
So why does McGrath make it? He isn't stupid. I think it is because modern rationalism, being descended from enlightenment rationalism, absolutely requires a certain kind of mythology to exist. It needs the great spirit of science. For the sort of history of science implied above to be true, you need giant spirits who don't slowly and painstakingly advance the work of lots of other scholars but who have "great insights" that change the world in a flash; always doing this despite great opposition by the humble peoples.
This mythology is so important that historical accuracy, something that usually matters a lot of McGrath, isn't so important in a movie that supports the mythology.