A guy this size doesn't last 12 rounds. He will gas out badly and get destroyed by any top 20 fighter with medium stamina.
He's not fat for a normal man, but he could lose 40 pounds and be a better boxer. You can see the love handles and lack of definition, although I would never have guessed that he weighed nearly 300 pounds. That must be a lot of weight lifting and not much cardio. If he had good trainers, then he wouldn't look like that.