I'm not sure of the context you are discussing this in, but while you are correct, that outside of Comm games, NZ 7s payers are never AB contenders as well (at any one time). So many All Blacks have had stints at 7s, and there are a bunch more that will be ABs that have spent time in 7s already.
Guys like Eric Rush, Cullen, Lomu, Muliaiina, Rokocoko, Messam, Kaino, Dagg, Jane, Piutau, Vito, J Savea, Barrett, Naholo to name a few, and you can pencil in Akira Ioane and Ardie Savea as well!
Again I'm not sure what the context is here in terms of Argentinian Rugby (as the interview is in Spanish), but if it relates the improtance of the sevens programme to the National team (and rugby as a whole in the country) then they should all be very much aligned! It is super helpful in the development of these guys. It gives them exposure to high level proffessional rugby, develops their skills, their fitness levels & in particular readies them for top level rugby often at a stage of their playing career where many would not get much of a look in even at ITM level let alone Super Rugby level. It really is a great development tool for NZ rugby!