From what the article says, it seems to imply that simply being in the KDE accounts file (a list of everyone who's able to commit to KDE) puts one in the "KDE" camp. That's almost certainly a bit misleading since many of the early engineering hires at Trolltech were KDE people who for more than a decade have been more "Qt" than "KDE". Also, since there are obvious dogfooding benefits to using a desktop built on the toolkit you develop, there are a good many people who worked for Trolltech (and later Nokia, then Digia) who used KDE and would have accounts created to commit an occasional patch.

A more interesting metric would be to see what percentage of Qt commits come from people who commit more to KDE than they do to Qt (and vice versa). As such, this just seems to establish what everybody already knew -- that the two projects are very intermingled.