There is a huge difference between iOS and other platforms.
Apple, in legal terms, makes Firefox on iOS impossible. This was not the case with Windows; Microsoft was using covert means to undermine user choice.
To make a blanket statement that Mozilla thinks Apple's banning Firefox from iPad and the iPhone is 'not a problem' is wrong and disingenuous.
We have active projects around ways to give users choice within the constraints of Apple's licensing.
Mozilla fought and won against Microsoft's anti-competitive efforts, under an entirely different technical and legal landscape.
As a Mozillian, I'm pissed and have been pissed off since iOS's launch, but we also have to choose our battles on where we can fight to keep the web open.
To apple's credit, they've provided a web standards based browser to a mobile landscape that didn't have one (at the time) and which spawned many other web standards based browsers like Chrome.
Do I wish Safari on iOS have a freaking file input so I could upload photos from the gallery? YES! Would I want a Firefox browser that was proxy based to get around iOS licensing.... hell no. Is it worth the Mozilla community's time maintaining an iOS based port just for the people who jailbreak their iOS devices... probably not, but no one from Mozilla would stop you from doing the work.