It would be awesome to have these to make maps with, even though I'm not really into that anymore.
I understand your concern, and honestly, the only (tedious) way of making sure no one uses them for commissioned maps is to have people ask for the link, tell you what they're using the meshes for, make it clear that they understand they can't use them in commissions, and you PM it to them.
While it won't stop them from sharing these meshes with those who don't know they are not supposed to, it'll at least give you a hand in it..
That's kind of an extreme sort of thing though haha