Why are you assuming the rapid increase in LA’s population from 2006 to 2010 did not have a significant portion of temporarily displaced people moving back?
Oh, then you’re of course aware that many many people did in fact return, and that your earlier estimate of the number of people coming to LA after 2005 that hadn’t lived there before was over-estimated.
Like, there are entire journals and programs of study devoted to it. I’m not just guessing here.