It is just that. It would be the most restrictive license yet used for anything required. If this was brought in, anyone distributing binaries will also have to make available the source code to the Qt that they used for example or not bundle it. Wxwidgets made sure those conditions did not apply to derived works distributed in binary form. The creators of Qt got dragged a bit towards it even being as unrestricted as the LGPL in the beginning. I had noticed that the licenses picked so far are all much less restrictive and had thought that was a deliberate choice to keep the software free to more uses without the burdens of the GPL
I can't imagine a better way to keep the software freer than with the likes of the GPL, but I suppose that's beyond the point. If copyleft should work its way into the main branch, as it might with the inclusion of Qt, folks who don't like it can just work with their own non-copyleft branch.
Yes, someone could always fork that last branch before that and probably will.