I don't want to pay for the game and yet have to risk my account being banned by them as well. That is why I prefer to cancel my pre-order instead of using proxy/VPN to circumvent the region lock.

Anyway, have anyone here tried Amazon's Ace Combat Assault Horizon Steam DRM? Can it be use to activate in our region? Without resorting to proxy/vpn of course.

Not so sure about that, but as I mentioned above, you can try to ask here https://forum.lowyat.net/topic/3087425/+1040&#entry65686901