Actually it seems to be more like Apple allowed VLC until somebody (actually a VLC developer) told Apple they needed a system in place for distributing the source as well as binaries.
Not only are Apple unwilling to allow that, the GPL forbids restrictions such as Apples 5-computer limit (or whatever it is), so it's completely illegal for Apple to distribute VLC under these terms but that doesn't matter until somebody complains.
So, Apple aren't even allowing developers to chose more liberal licensing terms than what they're used to.
Firefox isn't made for iPhone - Apple additionally have that rule where you can't submit software that mimics iPhone functionality (Opera has a license, im sure. I don't think this rule was lifted). Certainly if these rules weren't in place Firefox would be on the iPhone.