HomeSteak sure but Nwaneri wasn't getting into the Arsenal team either while Saliba, White and Gabriel were. Also while I take your point that getting into a national team isn't a certified mark of quality, by and large I'm sure you'll agree the outstanding talents of the nation usually start for their country.
It's not just Ellliot, Nwaneri wasn't a stand out for the U-21 in this tournament this when he did feature. Essentially two sets of coaching teams - Arsenal and England - have decided that he's not quite there yet. That's not a big deal for an 18 year old at all but it's risk for us to assume he'll make the step up in 25/26.