Fracturing it like that would be a surefire route to killing it. All the successful BSD projects have a defined trunk, regardless of being able to be taken proprietary as that's the only way for such a project to survive.
MS would love a BSD Qt, they could take and borrow stuff freely without concern of license violations or having to contribute back to the developers.
The worst thing that can happen is he tries that and KDE decides to force the issue and fork it. They can take the GPL and LGPL license and run with it. No BSD license, no proprietary licensing schemes.
Much like other unresponsive managing bodies (that passively or actively ignore user complaints, like XFree86), they can be bypassed by virtue of the license. You'll have to change the name, but like LibreOffice and Xorg, it will become the new trunk and the old, dead branch will wither.