Remember: “Free as in freedom, not free as in beer.” Selling open source software has always been explicitly allowed, as long as you make the source available to those who receive it. Check.

But they are asking you not just to delete their own software, but to delete the entire distro, which includes the Linux kernel and GNU binutils. Those are free in both senses and protected by the GPL, and a third party cannot just tell someone to delete it even if they distributed to you.