There's definitely room for both interpretations. 70.2 and 70.3 both using the word "remaining" leaves open the argument of "stuff that wasn't there to begin with didn't remain, as remain implies it was there to begin with."
But the new models do exist now, and they certainly were not destroyed. And it's also possible that the writers of the rulebook had no idea models would ever get added to a unit (they did have to add the rules for that in Maro's box, when you think that's something they would just include in the core rulebook) so they used that wording because it's the easiest way to say these things.
I can't wait for that FAQ... this forum will become a lot less "I dunno, could be interpreted either way" when we get some solid answers.