I didn't say he fixed it for everybody.
I didn't say anything about Badspot "fixing it" for a few people. That doesn't make sense and there's no reason for him to edit something so minuscule for a few people.
Nope. When this breaks the TML, it uses the last <color:ff00ff> thing in the chat string. Slayer changes that color depending on your team, so the same thing will happen, just with different colors depending on your team.
So basically it prevents < from turning red in most cases.
Try typing a message with < before it in a Slayer mini-game (not teamchat).