In reply to J K Hoffman.

"So, again, I'd spend time on a carefully worded support agreement, if anything."

IANAL, but I find it hard to believe that a clause could be legally binding if it construes as "abusive" behavior by one party that which the other party has explicitly licensed to be done.

"Honestly, I think in actual practice, few people will steal and resell the work/code, in spite of what people are afraid they'll do."

Redistributing a work licensed under GPL, which explicitly allows for redistribution of the original work and distribution of derivative works, is not stealing.

If you do not want your copyrighted work to be redistributed, then do not distribute it under a license that explicitly authorizes redistribution. If the GPL is not a suitable license for you, distribute your work under a different license. But it is immoral to distribute your work under GPL, and then to attempt to coerce those to whom you have distributed your work against engaging in the activities explicitly authorized by GPL.