The idea is to avoid having to face hardware competition. When potential competitors know that Apple has an advantage like that, it subtly encourages them to go into a different line of business. Which means that even if Apple never exercises the option, they may have gained value from having it.

Certainly discouraging hardware cloners has been a past priority at Apple for decades.

That said, I strongly suspect that your analysis (based on a far better understanding of the history than most of us possess) is correct.

Cheers,
Ben