I would honestly tell him to either start the manga from the beginning and read it (no non canon material) or since it sounds like hes in the war arc, maybe start reading right before that? Like around page 500, when Naruto's birth is revealed and Kushina is introduced and stuff cuz after that, shit gets serious lol
I wouldn't bother with the anime until hes read the manga, that way he will know the difference between the canon and non canon and the further he gets into shippuden anime, the more canon like or interesting it gets. I do like to say fillers aren't canon but these last episodes over the months seem to state otherwise. The kakashi anbu arc for instance seems pretty canon despite it not being in the manga. It just fits!