The Qur'an is in Arabic, I'm asking you how to refer to them in English so that maybe then you'll see the issue at hand. It refers to them I guess as "those who believe in what was revealed to you". I know your hoping I say "muslim", but that's not true, as the Qur'an also correctly referred to Abraham as "muslim", and all of the other messengers, and their followers as "muslims". I'm specifically asking as to how to refer to the followers of Muhammad, and Muhammads teachings. Do you have an answer?

"Go read the Song Of Roland."

The Song of Roland is a poetic work, not a work of scholarship. I seriously doubt the scholars calling followers of Muhammad Muhammadans thought they "worshiped" Muhammad. And if they did, arguably they weren't that good of scholars. The fact is that Muhammadan was the term to describe these people among essentially all Orientalist scholars, not just those who though they worshiped Muhammad. As far as I know, the Romans too referred to them as Muhammadans, as did their fellow non-Muhammadan Arabs.

"go bone up on your history of Western scholarship on Islam"

It's also not linguistically correct to refer to the Muhammadan religion by a name "islam", as the religions of Christianity, and Judaism are also centered around "islam", or "surrender" to God. Maybe you should brush up on your Arabic vocabulary.