Jon Jones is 6’4″ 205 pounds and Floyd Mayweather is 5’8″ 147 pounds, so the logistics of a boxing match wouldn’t work. It would be like Mayweather fighting in the heavyweight division.
From my experience boxers wouldn’t do well in MMA and MMA fighters wouldn’t do well in boxing. They are both fighting sports, but totally different when you really think about it.
Here is what Jones had to say about Mayweather.