I can't speak for Wyoming or CO, but I have lived in ID and I think Montana has hands down better hunting and fishing than ID. No offense to you ID guys. ID has a whole lot of public land but much of it isn't very accessable without outfitter etc., at least in the southern part of the state. Montana has a lot of public land that is very accessable. also if you get to know some folks, that can get you a long way too on private land. And as far as fishing goes, IMO there is simply no comparison.
I would recommend he look at the different state's hunting regs and opportunities online.
One other thing to consider...Montana is not the best state for work/employment. The average wage is very low compared to the rest of the country. If he can land a government job in the forest service, etc., he could get a good steady income with some benefits.
You will never know how much it has cost my generation to preserve your freedom. I hope you make good use of it.
~ John Quincy Adams