I'm pretty sure he played there for Leinster a bit in his first season because it was (mistakenly) assumed that it'd be easier to introduce him to professional rugby there than throwing him straight in at 13, before people realised pretty quickly that there was no need. He could probably do a job as in-game injury cover but going into a game with him playing there being a serious possibility would be a bad idea. He's been a 13 more or less all the way up, I'd say over 95% of his rugby has been played there, moving from there unless absolutely necessary is leaving us much worse off both at 13 and whatever position he's being shoehorned into.
I think we largely agree, I was referring to the possibility he could move out if needed due to injuries during a game. Not to the idea of benching him as a versatile winger/centre sub. I firmly agree he should be our starting 13.