You perfectly can sell GPL code. And you can double-license yourself (provided that you are the copyright holder) as GPL and a privative license. A lot of companies do that, legally and correctly.

You can sell GPL code. Even if you aren’t the author. What you must do is share the code with those customers though.

He didn’t want Signal on FDroid because surprise surprise he just wanted to roll their own crypto coin with insiders knowledge. You can’t do that with open source so easily. There’s a reason they didn’t publish code for years. That people still support those crooks, who have lost all credibility, for a privacy app, baffles me.

Thank god we have Matrix now.

Newbies don’t need that when starting, and at least they will have a solid ground to work with.