Yes, the car driver has made some severe errors of judgement in how and when he overtakes, how he has not really gone fast enough to complete the manoeuvre in the space he has, and how he has misjudged closing speeds. A professional (or merely competent driver) should see that, and for the sake of lifting off the accelerator for a few seconds, let the person in for the greater good of preventing someone else having an accident (which for all you know you might get caught up in).
If I see another driver getting themselves into trouble, I'm not going to be an ******* and block them out when I can safely give them a way out of the bad situation they've got themselves into. We've all made mistakes on the roads, there's no need to make those mistakes worse when you can help someone. When it's obvious you're both going to end up at the same place at the same time and you can prevent that from happening, then it's important to do so for everyone's sake.
