That post was nothing to do with the security incident in question here (which happened April 11th 2019; that post is from March). The details in that post are sadly true (as others confirm on that thread).
However, we have no reason to believe there was a link to the April incident.
yes, and he was, by his own admission: repeatedly bragging about exploiting bugs in Matrix’s beta design which we hadn’t fixed fast enough in his estimation (hijacking Matrix HQ; bricking #matrix-dev; threatening to loop over all public rooms to brick them unless we paid him; etc). It wasn’t exactly subtle, and it’s bizarre if you think we’re making this up or presenting without evidence.
However, the matrix.org security breach in Apr 2019 was unrelated to him, as far as we know.
However, we have no reason to believe there was a link to the April incident.