There is the requirement to make the source code available (GPL), as far as I am informed, you can sort of get around this, by delivering the source code with the download, but then "don't advertise" it, as in hide it as much as possible without getting in legal trouble.
(My information may be a bit outdated here) Afaik, the Blender Foundation doesn't even bother to shut these projects down (they do get frequently informed about it, when people discover it).
And this even given the fact, that they would be easy to shut down. The reason for this, is used media in advertising. If you want to sell your 3D package, you need to show some impressive artwork which was created with said project.
Problem is, the images/animations these projects show off on their websites are a) not created with said Blender reskin, but usually in Blender itself and b) they usually don't have permission from the artists.
So even having this quite comfortable handle, BF usually don't care. Which tells a lot about the impact of such copycats.
My takeaway from all this is, the situation would pan out pretty similar for Defold, and they should just dare it and monitor the landscape.
Also, it seem like the really important point is kind of glossed over. Base64 is not a kind of encryption, it's an encoding that anybody can easily decode. Using it to hide secrets in a GitHub repo is a really really dumb thing to do.