He's a punter, so he can kick, but I suspect he can also run fast and tackle. Since these are valuable skills in 'rugby' it's understandable that he might think he would kill it. What he doesn't understand, along with so many people who have watched the sport for decades, is that it is your weaknesses that determine how far you go in rugby. Or at least in rugby league.
Kicking for height and distance is only a small part of what a 'rugby' kicker does. And cover tackling a 90kg punt returner once a game is very different from having to make first contact with the ball on some linebacker-sized merkin running straight at you, not to mention the endurance component.