You could say that for any word. The common people's definition of prominent. In the sense that he wasn't that known in the tech world and not a household item in the business industry either.
I am simply observing the general meaning of unknown in the context of statements like this in the English language. I suspected that the person I was replying to might be unaware of this meaning based on their reaction, and was trying to clarify. I really don't think there are many assumptions here. This is by far the most common interpretation of unknown in sentences like this.
