Personally, I think that it was a good decision.
It's not about politics, religion, etc. themselves nor about how much heat they usually attract. It's about the fact that it simply adds too much work for the mods, imho.
When comes to these topics, people simply can't keep it calm.
I'm not sure about that, most people can keep it calm talking religion politics or whatever. There's a few who can't and flock to threads, but its not the subject matter that does it though. The same people can't keep it calm over the video game either.
Politics is a very hard thing to keep out of any discussion as it effects absolutely everything, so personally I think the ban was more to stop it cropping up and turning nasty in all sorts of random threads rather than the topic itself being a poop-magnet. Having a politics section would spill over into the rest of the forum so a flat ban makes sense.