I'm not sure what to make of this type of behaviour. I can only think of two possible explanations:
1- Narcissism: Any blow to a narcissist's ego sees the narcissist in question lash out. An example in football might be Jose Mourinho. On this case, Dustin humiliating him on a worldwide stage, denting his legacy in the process could have resulted in the perplexing level of anger, vitriol, and hatred that Conor seems to have towards Dustin.
2- Showmanship: Perhaps he isn't mentally unstable, but is choosing to engage in some pretty unstable behaviour because he thinks that rant at the end could set up a 4th fight. Or perhaps he tried to antagonize Dustin to set up a brawl that would dominate the next day's headlines instead of Dustin's performance.
In my opinion, there are lines that shouldn't be crossed and the latter shouldn't be invoked as a defense when people rightfully call someone like him the pejorative you just did. He's a clown. And I'm glad there has been backlash to his actions because this type of behaviour should not be normalized, moving forward.