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.

You called him malicious/dangerous and said he is involved in an ongoing campaign of exploiting security vulnerabilities in Matrix.

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.

Which is not what you claimed.

That's how I perceived it.

Maybe you want to look into your perception of the world in contrast to facts. Some bias in there apparently.

Based on what was said by Arathorn, it would be easy for anyone to perceive it that way

It would be easy to perceive Arathorn to be talking about some future event instead of the protocol issues he mentions earlier in the same comment?