No it's not fine. Lesson time: Analogies actually have to be alike in some way. You can't just say "this is like" and have it be true.
Let's look at the Leaf vs Frontier. The Leaf has physical characteristics that make it far less capable than a Frontier (even if a trailer hitch was added). The same is not true of the iPhone vs the Mac. If artificial restrictions were removed (i.e., not including a trailer hitch, or limiting apps to the app store) the iPhone would outperform some Macs. No similarity, so the analogy isn't applicable.
So let's try a different angle. Let's a assume you added a trailer hitch to a Leaf and it could tow small loads. The Frontier could tow whatever the Leaf tows, plus much larger loads as well. This could be similar to the iPhone running iPhone apps, and the Mac running both Mac and iPhone apps. However if you go back to the Leaf with the trailer hitch and say it can only tow Nissan branded trailers for "safety" purposes, while the Frontier can tow any brand; that would make no sense. So the analogy couldn't be used to support the idea that iPhone apps must be restricted to the App store for "security" purposes.
The Leaf vs Frontier analogy is bad because it bears no similarity to iPhone vs Mac. Different tools for different jobs? You'd be annoyed if your tools were artificially limited too. Instead of adding more bad analogies to the pile, why not try to explain why the first one fits if you think it's so good?
PS: Whether you agree with Apple's position or not should have no bearing on whether you think an analogy is good. A poorly written point is still poorly written even if you support the position they are trying to argue. Similarly, someone can make a good point that you disagree with. I've posted this in the odd chance that someone might actually try to generate better analogies in the future, but I'm not going to waste more time on it, unless someone makes a solid point.