I don't think anybody, including Mullenweg, is seriously claiming WPE is threatening the integrity of the WP.org servers with all their load. It seems pretty clear that WP.org is a stick the Foundation is going to use to get commercial WP users to kick in resources, along with the WP trademarks.

The norms of open source software don't really have much to say about this. Mullenweg is right: the typical thing companies that run GPL projects do when they end up competing with firms that don't pay their freight is to relicense. Being a little ruthless with trademarks seems strictly superior to switching to a "source available" license.