Ehhh... Whether or not it happens with one person really doesn't say whether or not it's something that will happen with everyone. Zircon is a talented guy, and he's really made a name for himself outside of OCR with his music and business (which is a pretty awesome feat, by the way), but for every Zircon out there there's plenty of people who have Willrock's experience of virtually no audience transfer. I'm sure having an audience for your arrangements doesn't hurt your chances as a popular musician and/or accomplished composer elsewhere, but there's evidence (at least in this thread, anyway) that it can be a pretty insignificant boon for your other endeavors.
A combination of how good you are at marketing and networking is more likely going to give you better luck in having a large audience for your original work than having a large audience for your arrangements, I suspect, which Zircon also has quite a knack for. I understand that it can seem fruitless to logically discuss something like whether or not audiences transfer from one person's composition styles or not, but let's be honest - that's a pretty relevant thing for a lot of arrangers who want to make a living off their music in the future. Whether or not the audiences transfer from your free releases to your work that you profit off of could easily impact whether you're willing to arrange video game music, in the first place (which is how this topic cropped up in here).
If someone could crack that nut and figure out how to effectively transfer their audience, that'd be a very useful thing to know. It's at least an interesting and relevant topic to discuss, imo.