The legal threats against WPEngine and their customers, the lawsuits between WP/Automatic/WPF and WPEngine, the banning of several contributors, the takeover of WP Plugins on WP.org, the shenanigans with several check boxes on the login pages of WP.org.
While it wasn't as damaging from a legal or (business) reputational perspective, he also peeked into the Tumblr database in order to doxx people who were making fun of him, which doesn't say great things about his stability or fitness to run a company.
the author of that email has been having a very public breakdown for months now, mostly consisting of being a prick and trying to harm the community and a competitor.