According to Twitter employees on platforms like Blind and news sources, Twitter (the website) is the only datapoint for communication with their new boss.
1 - according to a lot of reports from other people fired these past few days, there is no internal conversation about anything substantial, they learn more about his point of view and/or what he doesn't like in their job from his twitter posts
2 - no matter what, as a manager you are the "face" of the team and while internally you are in charge of letting people know what's wrong in their code etc ... It is extremly bad form to push the problem down to the members of your team when talking in a public facing situation. You're the manager, it's your team, you're the face, and you're also the face of the problems. No matter how deep down or high up in the chain you are, if you manage a team and behave like what Elon did in the original tweet this guy answers to, I guarantee you no one on your team respects you.
3 - the guy is in a firing spree to try and justify his overpriced unwanted purchase, and then goes on to take a dump on the work of this engineer in public with a factually wrong comment. No matter if you're my employer, you have no right to damage my reputation based on false allegations in public just to help your ego.