I don’t think it is.
The second link shows that there is no explicit user trust or any extensive research in reasons to trust the ~1000 (or whatever number) of Fedora packages. There is just someone who “liked” Fedora at certain point in time with no explanation how exactly that happened. So, it is not as simple as everyone trusting Fedora and whatever comes with it in dom0. There is rather an inevitable forced trust due to lack of options and that is more complicated than “I trust ~1000 packages from Fedora”. Even if it was the latter, it is still not a valid reason to trust another N packages, thus making dom0 even more bloated. Hence my question regarding KDE.
On another note, if you have some work that would bring your vision of minimizing in QubesOS closer to reality, I am very interested.
This thread (not my work) was an interesting start: