There is a question, but the part about the monopoly was in the setup, not the part being inquired about. It asked "how can the app store promote competition when it is a monopoly on iOS?"
The second part of the question is assumed. To question that part, one would ask "how can the app store promote competition if it is a monopoly on iOS?"
Maybe it's my locale (California, USA), but where I'm from, "What you're doing is assuming" is a very condescending response to someone asking a genuine question, and can only be found on the internet. But, perhaps my locale is why I perceive this as odd, rather than it being odd.
I'm a CA native myself, and I don't talk the same way I write. In person, I probably would have said something like "but you're assuming away the key legal test, which is 'what is the "relevant market?"'". I tend to not go back and edit my comments for style, just for clarity. Could it be more polite? I guess, but it also seems pretty consistent with the logical/syllogistic style that is common on HN.
I thought the question was not entirely in good faith, since it would be pretty obvious that there's no such thing as "monopoly on X" — otherwise it would make Sony a monopolist on Playstation, Microsoft a monopolist on XBox, etc.
The second part of the question is assumed. To question that part, one would ask "how can the app store promote competition if it is a monopoly on iOS?"