Correct. This is also why Apple switched to zsh as the default shell over bash. They still ship Bash 3.2 in macOS, because from 4.0 on, Bash started using GPLv3 instead of GPLv2.

I'm not against the idea of creating proprietary software out of open-source software, if the license allows that. However, I am always against this practice of "closing the door behind you".