I have been asking this myself almost all the time when the drama with nvK and his policies came up. I didn't want to follow it closely, therefore I don't know much about the details of licenses of the source code nvK's company used when they built ColdCard firmware.

In my opinion it's a shitshow and an embarrassingly bad one, too. You simply can't argue that you have heavily modified the original code and made your version much much better. It still originates from some license and you have to follow that. It defies the purpose of open-source if you change the license at your personal ego will.

But frankly I lack the knowledge of all the shitshow's details as I don't want to devote time of my life to it.