From the various blogs I've read, even if you use a Malaysian IP to purchase your gift cards or your e-books, Amazon will just ask you to confirm your address. Then you confirm as US. That's it. It's more of an annoyance.

If it ever becomes worse than that, you can always take precautions by using Hotspot Shield. Look it up. There will be annoyances and problems, but I haven't come across anyone who had to throw away their Kindle because of the Malaysia limitation issue.