I may be generalizing incorrectly but given Mozilla's lack of comment either for or against the W3C DRM initiative I think they're not wanting to jeopardize partner arrangements by saying anything negative. Even if they have no deals requiring DRM, why turn off potential partners with statements that don't need to be made yet.
Usually they're publicly all over this sort of thing. I don't see any Mozilla people commenting in this thread about what they think either which is unusual but probably wise.
On the other hand I don't see statements from Opera either and they're usually pretty anti this sort of thing. Maybe they're both doing behind the scenes work to scuttle the DRM initiative and don't want to make it public yet.
Not supporting it would be bad for Firefox OS. It would mean that platform is locked out from streaming video solutions (ie. Netflix). This would discourage carriers from supporting Firefox OS. On desktop it doesn't matter so much. They have a marketshare to make a difference when they take a stand. However now that they're in the phone market, if no carrier will take Firefox OS due to the streaming video issue then the OS is dead before it really begins.
They stopped opposing H.264 once they needed it for Firefox OS. I'd expect Mozilla to support the W3C DRM stuff as soon as someone makes Netflix a requirement for their Firefox OS phone. Maybe it won't be Mozilla but someone shipping Firefox OS will do the work. Then Mozilla will feel pressure to take the patch they provide. They're in a difficult position now that they're in the mobile phone OS market.
Usually they're publicly all over this sort of thing. I don't see any Mozilla people commenting in this thread about what they think either which is unusual but probably wise.
On the other hand I don't see statements from Opera either and they're usually pretty anti this sort of thing. Maybe they're both doing behind the scenes work to scuttle the DRM initiative and don't want to make it public yet.