I thought we would have a license declaration of the logo in the Picard repository, but the AUTHORS.txt (which should get updated anyway) only says:
Picard logo by http://monkeydo.digital, © 2015 MetaBrainz Foundation
That makes things a bit vague here. Depending on interpretation one could either assume the license follows the same license then the rest of the repository or that it is copyrighted without any usage license, which would be problematic for distributions. I guess we should also update the text here similar to what @fhe proposed above.
I think it would also be great to have some usage information / guidelines on the logos in general with some info what is considered legitimate use.