Also worth pointing out:
There are other issues too. All of Law and Blair’s tests were done with one kind of 3D printer—a Prusa MK4S. There’s hundreds of different devices on the market that all behave differently. Law also pointed out that brass nozzles warp over time themselves and may produce different results after hundreds of prints and that different nozzles made from different materials may work very differently. Law would also want an examiner rate study—a formal scientific inquiry into false positives and examiner bias.
You can profit from GPL software. The only restriction is if you distribute it you also need to distribute modifications under the GPL.
GPL also does nothing for software as a service since it is never distributed.
GPL even explicitly allows selling GPL software. This is effectively what redhat do. They just need to distribute the source to those that they sell it to.