Hell, they could even make it Open Source with a clause preventing other companies from using to code to make a profit. It's too big to fail.
Such a clause would immediately make it Source Available not Open Source.
nowadays github is filled with so-called open source projects under GPL3 but the maintainers want you to pay for a dual license
> The license must allow modifications and derived works, and must allow them to be distributed under the same terms as the license of the original software.
> No Discrimination Against Fields of Endeavor
You cannot restrict selling derivatives of the software (a field of endeaver), and the derived work must be able to be shared under a similar license.
GPL does not add any restrictions counter to that. It allows you to redistribute and sell copies if you want, you just have to respect your user's freedom by also giving them the modified source code.