Even with the possibility of obtaining gag orders, the risk and potential to exposure to Apple would be huge.

They'd be in much safer territory to just not include encryption software with their products at all, unless the whole NSA surveillance thing is so complex and intrusive that they force large OS makers to specifically develop backdoored encryption technology for the specific purpose of encouraging people to store sensitive information on FileVault encrypted drives so that the government to access it at it's will.

But, that doesn't really stand to reason in my mind.