This question is really philosophical and mostly not fruitful, as both views are valid, depending on where you look from.
Like BSD vs. GPL, it is always the freedom of one person or group vs. the freedom of all others.
We therefore wont comment on this debate.
Linux is based on Richard Stallman’s philosophy which is GPL. The licence CC-BY-NC-ND and CC-BY-ND is incompatible with Linux and GNU philosophy.
As @opendesktop answered both are valid, you can keep your works closed-source. The fault is not of the forkers or the author of La Capitaine. It was of your friend because he could have put CC-ND instead of GPL3, in the repositories El General 3 years ago and Antu 2 years ago, for preventing the author of La Capitaine of forking. It was too late.
As your friend is not in favour of forks, he is in the wrong operational system because fork is a symbol of collaboration, which is inspired by the GPL philosophy. He can work at Microsoft. Matthieu James was a famous icons designer of Faenza and Faience, abandoned Linux world and Canonical and went to work at Microsoft.
Plus, since your friend likes to sue the forkers for violating his licence, he must be an ideal for being a CEO of Apple because Steve Jobs sued Google for plagiarising iOS to create Android.
That’s your problem with Fabian, I use the CC BY-NC-ND for a long time (since the Helium 1.0 that was published a couple of years ago)
The problems I have had with using that license have practically been against free software extremists and people who want to fork to earn money easily.
Most artistic works use CC licenses because it is made for that area.
I think we should stick with each other, if the opendesktop website does not accept the licenses of their jobs simply withdraw, if they are not here for the money then maybe it’s not worth bothering
Already my account has almost a decade in this place and it bothers a bit the situation. But reading the licenses that they left I found some that could be very useful knowing how to adapt.
I hope that you find a license according to your needs,
although it is worthwhile that you consider the option of releasing your work under a license compatible with GPL., from some forks work very good, many of the current big projects are forks, and the world of gnu linux would not be the same without this philosophy