His reasoning makes sense - I picked the right answer
However, he overlooks the more important aspect of PL position. It's not the fact that all-ins will take away positional advantage on later streets, it's the fact that in PL, you can check behind and force the size of the pot to be a fraction of what it would have been (because he can't overbet on later streets). On the other hand, a value raise can win much more than a value bet because of the pot limit.
Negreanu explains this to some degree on a WSOP
video. If I come by it again, I'll link to it.