Things could change. That why it was brought up for debate. The debate could have concluded that changing defaults is not the right move.
It really is a branding issue.
And what would be the trademark(!) issue? The default desktop edition is called "Fedora Workstation", not "Fedora Gnome", so the branding is not tied to Gnome in any way. Seems more like an attempt to kill a discussion where the popular vote might be undesirable.