Earlier quoted context omitted.
Man in the middle interfering with TLS handshakes? The handshake is unencrypted so you can modify the messages to make it look like the server only supports broken ciphers. Then the man in the middle can read all of the encrypted data because it was badly encrypted. A surprising number of servers still support broken ciphers due to legacy uses or incompetence.
No: while the handshake is unencrypted, it is authenticated. An attacker can’t modify it. What an attacker can do is block handshakes with parameters they don’t like. Some clients would retry a new handshake with an older TLS version, because they’d take the silence to mean that the server has broken negotiation.
Then you can MITM, force both sides to use the weak crypto, which can be broken, and you're in the middle. Also not really so relevant today.