It's a very appropriate argument, and Ford does have a monopoly on F-150's. As I've noted elsewhere, monopolies are not by themselves illegal.
The trucks are like the iPhone, so in this context we would be talking about truck parts (i.e., apps). Ford doesn't restrict or attempt to control the market for F-150 parts. If you damage your car, the mechanic can buy parts from Ford or any one of dozens of auto parts makers. In contrast, Apple does restrict and artificially control the market for apps, even to the extreme of drowning out competing apps with irrelevant search results, and Apple is the only market for getting iOS apps.