Of course, though, you can use whatever you want. Just like those people using words like "Camie" and "Gorilla Company" and "Gadus".
Erm, what´s so wrong about "Camie"? It most certainly works with the Katakana we have while Gorilla Company and Gadus don´t work with their respectives Katakana.
Furthermore, what´s not in the manga doesn´t count. If we´d go by that then you can point out lots of contradictory romanizations ins merchandise articles. I also prefer Brook. But merchandise spellings are not the best indicators for anything.
Last but not least, why is this thread still open?