Hmm, I swear this must be new since last time I checked the Blender site, but it seems to address my concerns very succinctly, and apparently that's not relevant:
> Sharing or selling Blender add-ons (Python scripts)
> Blender’s Python API is an integral part of Blender, used to define the UI or develop tools for example. The GNU GPL license therefore requires that such scripts (if published) are being shared under a GPL GPL compatible license. You are free to sell such scripts, but the sales then is restricted to the download service itself. Your customers will receive the script under the same license, with the same free conditions as everyone has for Blender. Sharing Blender or its scripts is always OK and not piracy.
This one looks like standalone application, that has integration plugin into Blender. Otherwise, you can export into other 3D packages and not use Blender at all.
By the same token, anybody who distributed a fork of the said script is free to charge for it as well, as long as the source code (or patches thereto) is/are distributed under the GNU GPL or compatible license.
> Sharing or selling Blender add-ons (Python scripts)
> Blender’s Python API is an integral part of Blender, used to define the UI or develop tools for example. The GNU GPL license therefore requires that such scripts (if published) are being shared under a GPL GPL compatible license. You are free to sell such scripts, but the sales then is restricted to the download service itself. Your customers will receive the script under the same license, with the same free conditions as everyone has for Blender. Sharing Blender or its scripts is always OK and not piracy.