Me: Why isn't BTC bitcoin then?

You: Because it has high fees that prohibit it from truly acting as "cash."

Me: But BCH also has fees.

You: Yes but they are very low.

Me: But it still has fees. They both have fees. Just because one coin has lower fees than the other does not mean that one is cash while the other is not. You are making an arbitrary distinction and using it as a semantics-based talking point which fails to detract from the fact that the broader community (users, merchants, exchanges and miners) has decided Bitcoin (BTC) is Bitcoin, and Bitcoin Cash (BCH) is an altcoin.

If you wanted to appear more honest you would concede the fact that the community does not accept your premise, nor is it likely to in the future, and you would rename your coin so it is no longer possible for others to accuse you of engaging in deceptive practices.