It can’t be done, of course. But, I think he can do 300 watts, or about 4:20. I think he did do 300 watts at Lake Placid. His 4:35 ride there stands as one of the greatest few rides ever done in any triathlon.
G.Byrn made an interesting observation about calories expended at those wattages. It’s hard to imagine anyone running well simply due to running out of calories. Your fitness can become overwhelmed by the calorie deficit.