Well, yeah, acting like a god and trying to work over or eliminate governments is exactly what he's tried to do repeatedly, from Lee and Kirby to Morrison and Quitely -- missiles, Asteroid M, Avalon, global EMPs, etc. It's just that there were others with godlike powers around to stop him.
I don't get the doubt and skepticism towards Magneto's powers in this thread. OP said Magneto, so everything he did the comics is fair game. Any scenario of "You with the power of X" is bound to be ridiculous, so take it and run with it.