Though I see no reason why EC2 would barf on it, as long as you support the proper hardware. They just don't include a lot of legacy hardware you find on a more standard bit of x86 hardware.
Now, if you wanted a really interesting article, discuss how to port your OS to run on the EC2 ARM instances!
I'm pretty sure EC2 would barf on that, even if you were running in 32-bit mode.