So the guy is the phenomenon of rugby... the best runner in rugby of all time and you say he wouldn't be able to cut it at any level of NFL 
Stats:
Height: 6'5"
Weight: 265 pounds
Speed: 100m in 10.8 seconds
40m in 4.8 seconds (it has been estimated this would work out to a 4.5 for 40 yards)
Looks good on paper, but I can give you a list of guys with better numbers who did nothing in the NFL. He runs high, and only looks good when he is bouncing to the outside, running vs smaller - nonathletic, tacklers. In traffic, he would be man handled by lb's his own size. He runs with extremely long strides, and does not change direction quickly or seamlessly. He wouldn't even make an NFL roster as a rb. He is WAY to tall.
Couple that with the fact that he does not wear pads, and there is no real defensive scheme. 350 lb defensive linemen would eat him alive. Maybe if he could catch the ball effectively, he could be a good NFL TE. Your comparing apples to oranges. The speed of the NFL game is so much greater than what you see in Rugby. Lots of guys can run and jump, very few guys can excel vs athletes of the highest level in a strategic game like American football.
I'm not trying to be a dick here.....the guy looks good, but he is running on the outside of the plays, free in space. Between the tackles he just looks like a big dude who has more size then the men trying to tackle him. I picture a guy like Demarcus Ware, lining him up and dropping him behind the line of scrimage with no problem.
"Stats" dont mean shit in the American game.