I port Custom_Morph (Morph Brush) modifications between figures all the time.  You can export a morph target from the Custom_Morph just like any other deformation of an actor.  You can also port the deltas by editing on the file level, or use one of the various utilities available to copy morphs between actors.

I don't see why there would be any problem with sharing or distributing morphs you've created with the Morph Brush, unless you are embedding a copyrighted morph into the deformations you seek to distribute.  The rule should be the same here as with any morph: if it's your own work, you can distribute it freely.  If it's derived from something freely redistributable, you should be able to distribute it freely.

The Morph Brush handling can seem awkward at first to some users, based on posts I've seen in the forum over the years, but it is a pretty simple process once you understand how the tools work.  The Morph Brush in recent versions of Poser is flexible and stable, and extremely useful.  This is one of the tools with which the Poser Team has done an excellent job.  :thumbupboth:

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Cage can be an opinionated jerk who posts without thinking.  He apologizes for this.  He's honestly not trying to be a turkeyhead.

Cage had some freebies, compatible with Poser 11 and below.  His Python scripts were saved at archive.org, along with the rest of the Morphography site, where they were hosted.