Why is WP.org entitled to selectively blacklist one downstream consumer and not others? Have they demonstrated that WPE is putting undue load on the infrastructure? Have they even alleged it until just now?

If wp.org is part of the foundation, then they have a legally binding mission, and "acting in Automattic's strategic interests" is not in there. If they're not, then a8c is intentionally obfuscating their ownership of wp.org, thus placing the credibility and legal status of the foundation in jeopardy.