Let's look at a few good reasons to stay silent if you're an Apple competitor.
1. Apple's competitors are based in South Korea and China. They're going to have a much harder time arguing privacy with the US government.
2. Apple has lots of money and excellent legal counsel. They'll put up a better fight than their competitors possibly could.
3. Staying silent won't piss off any American lobby groups, and it probably won't piss off the American general public.
4. This could be a PR nightmare if someone mis-words something. You don't want to accidentally paint yourself as pro-terrorist.
5. There's no obvious win here. If the corporations win and privacy remains paramount, eventually someone is going to do something awful that involves encrypted communication. At that point, the corporations look bad. If the government wins, things could devolve into 1984 if the wrong people ascend to power.