If you're running lights, having GPS or not on your dashcam isn't really an issue here, the video would've caught it anyway.
By the way, I'm failing to see the correlation of GPS to traffic lights...??
The GPS records location and speed. It can also set the correct time zone. That's about all it does, in my opinion you should only be considering whether or not you need that function, how much extra it'll cost, and weigh your options.
If you buy a dashcam with GPS only to leave it disabled all the time, then maybe you should've just gotten one without GPS.
If you're only looking to disable it when you decide to break traffic laws, then you either shouldn't be driving (because operating things while driving is a big distraction and a hazard to everyone on the road, not to mention you're intentionally breaking the law), or shouldn't have gotten a dashcam in the first place.
Please drive safe, I know we aren't all saints and occasionally go over the speed limit or run a light, so you shouldn't worry about it too much. If you can't handle getting caught, then don't break the law, the dashcam is merely a passive witness of your actions.