This point might be true or false depending on what makes someone a philosopher. In the end, Rand’s input to philosophy is limited, and not nearly as substantial as Marx, for example. Her style is also completely different, as where one was writing treaties and books, Rand focused on prose and narrative to explain her ideas. You can argue that from your local farmer’s POV, Rand is a philosopher - but that doesn’t make Rand a philosopher.
That aside, Rand’s status as a philosopher is tangent to the discussion, as what your friends accused me of was that my statement was unsupported - therefore arrogant. They demanded evidence of other people agreeing with my statement - and I did provide it. What better way than quoting philosophers upon that very topic, as was demanded by one of the participants? They were roasted,
You cited a source that explicity call Rand a pilosopher, and engages in her work as works of philosophy. So, you cited a source that disagrees with you. Rand is a philosopher. Deal. With. It.
Plato expressed his thoughts through Mary Sue fanfiction starring his teacher.
Again you did not. You provided evidence that she is not considered a philosopher of worth in academia, not that she is not considered a philosopher. The “rejection by most professional philosophers” line, in the context of the full quote is related to that rather than saying that she is not a philosopher.
That’s the sort of arrogance you only see from people who read a little about philosophy online and suddenly consider themselves experts. Those who actually study it tend to be a lot more respectful due to the importance of discussion in the process of studying the topic in institutions.