Or how about we set up a Mars colony, and do all of our wars there? Seems somehow appropriate. We can nuke the hell out of Mars and everyone on Earth will be fine.

And what makes people think that in the event of global thermonuclear war that Mars will escape unscathed? Absolute ridiculous nonsense. The solution here is not to run away, it's to confront the problem directly.

I never understood how anyone could think that "Earth is so messed up, with so many problems, it's just easier to colonize Mars." Earth is PERFECT for human beings to live on. Let's make it work.

An irradiated post-nuclear Earth is far more hospitable to life than Mars.

Very likely that anyone on Mars would still be very dependent on Earth to survive until proven otherwise; at that point, it wouldn't be surprising if, as a control, nuclear countermeasures were deploy to insure Mars was at just as much risk.