IMO since Whonix sits on top of Qubes it should follow the Qubes trust model as much as possible. So, for example, the Whonix template VM should only allow access to the Whonix and Debian repositories because that is the trust model the main Fedora template uses. Of course, just like the Fedora template that can be overridden by the user manually by disabling the firewall or by installing packages manually. But the defaults should match between Whonix and Qubes.