While a 270 lb offensive lineman can cut it at the Ivy League level, he's probably not going to be physical enough to handle a 280 pound defensive end for a whole game, much less a 300-350 pound defensive tackle. It's one thing if he were a true freshman or even a sophomore, but if he's 270 lb as a grad transfer, then he doesn't seem to have much upside. Maybe someone like Coach Balis could add another 5-10 quality pounds during the off-season if the Harvard S&C program were deficient, but again, that's a stretch.
It's a much different game these days when it comes to physicality in the FBS collegiate game, versus that which was played just a few decades ago. Players are much bigger and stronger, and can sustain that kind of strength for the whole game.
The days of agile 260 pound linemen (such as the most awesome Guy McIntyre) being able to out-finesse bigger defensive linemen are long gone. If anything, those guys are now closer to today's tight ends.
If his technique is superior, and he can at least play a dozen downs a game, I suspect that LSU will be using him as an edge blocker, essentially working as an H-back or blocking tight end. Even if there are a bunch of injuries on the offensive line, though, he'd probably be no higher up on the depth chart than the 2nd or 3rd "swing" offensive lineman. Think of his being a step or two down from Trevor Ruhland's situation last year.