Real question: Is there some social etiquette rule that says describing a person to a news audience as "unknown" is being rude? Honestly, I've never heard of that.
If I created a billion dollar company and Bloomberg called me "an unknown", I'd consider it a massive compliment. It means that I was able to grow the company totally under the radar without any distracting interview requests from TechCrunch, TheVerge, Gizmodo, etc.