You can distribute any pz2 (or other type of pose file) that you create from within the Poser interface. This is because the only information saved to a pose file created from within the Poser interface is the values for the various paramiter dials, and dial settings can't be copyrighted (in my opinion, I'm no expert on law). You can "Include morph channels in pose set", if you want, there may be technical reasons why this might not always be a good idea (perhaps the character that the pose will be applied to does not contain these channels), but there are no legal, or as far as I can see ethical reasons not to do this.