I don't think anyone will be confused... seeing as it's also the name of about a billion other things (Pre-Firefox, I still remember you!). I feel like "Pheonix" is the second most common project name behind "Matrix".
And on a less nit-pick-y note if the author is reading this - the project looks really fun and is certainly going to take up a chunk of my weekend!
[0]: https://www.phoenixframework.org