As the bitcoin logo appear in every search engine you can consider it free because it will not be uploaded if it is not open for public, it's logo were uploaded for the sake of letting all the country in this world know about the idea of crypto currency so it can be adopted or accepted, and for further is it's centralization.
True, it's free as everyone has been using it and those companies that will use it without permission will be sued copyright infringement.
But as others said it is for free so, we are all free of using it.
I think we all own it.
We don't actually own it, the logo is free to use for everyone as long as it's for bitcoin use and other relative use.
This is a good discussion, I didn't even thought about this before.