However, if DHH’s verbatim quote of his response is accurate, it sounds like things had gotten out of hand with this company’s culture.
If a leader says “this is unacceptable - we will do better going forward”, that should be enough in this kind of situation. But apparently it wasn’t for the employee that you allude to.
A third of the company had joined some D&I committee and that committee apparently felt that its scope extended to the entire operations of the company. It sounds incredibly disruptive.