Actually you would have a third recourse - to publish, with full knowledge that your photos might be used without your consent. Many people have and still do dedicate material to the public domain. Thus, your “fundamental principle,” which is “that the source for this code would not be available for public viewing if the author could not rely on downstream users abiding by limitations on the permission to copy,” is fundamentally flawed

I post photos to flickr using a Creative Commons license which prohibits both modifications and commercial use. Persons wishing to publish a modification or use the image commercially will need a different license which can only be obtained by negotiation with me. If the courts were to hold that this license is not binding, I’d have two recourses — all rights reserved or not publish at all.