The gnome mime database thinks OTF files are some kind of ODF file (as
documented in the ODF spec).
However the OTF extension has long been used for OpenType fonts with CFF data,
and there are many more OTF font files in the wild and even in linux
distributions than OTF ODF files.
Therefore the default should be switched to font file.
Even OO.o uses the OTF moniker for font files
I guess it depends on your perspective if you consider OpenDocument Formula Templates more or less important than otf fonts.
Anyway, the right component for this is shared-mime-info, and you should also report it upstream in bugs.freedesktop.org.
One thing we could do is add the *.otf glob to application/x-font-otf as well, and use the new glob weights to control which one wins by default.
The bug is already upstream at: