Of course, but you get steam key, activate the game on steam as usual, and don't give a shit.
Anyway, you may also explain that you were staying in a hotel in US during the purchase.
Of course it's not completely legal, but well, I don't care.
Also, I believe Crusader Kings 2 is worth more than 5.99 GOG, by the way.
Catshade: FWIW, I bought Mount and Blade Warband on Amazon, which was mistakenly labeled as Steamworks even though it's not. I e-mailed support and they promptly refund me and let me keep the non-Steamworks copy.
So Amazon doesn't give a shit if you lie about your address. Even better :-)
They probably are region restricted only to provide better deals, so they don't care.