It's a key design constraint of status.aws.amazon.com that it not depend on any AWS services. (Or so I've heard.)

status.aws.amazon.com resolves to 207.171.185.167 for me.

That IP isn't in the EC2 IP ranges (https://forums.aws.amazon.com/ann.jspa?annID=1528), so at the very least it's not hosted on EC2.

I thought I read somewhere that it was on Rackspace