But he's not 15, he's 16 (and a few months from 17). And there actually are quite a lot of goalies that are 6'4 at 15. For all those goalies that end up 6'7 or 6'8, do you not think they were at least 6'4 in the 15-17 age range?
My opinion is that he does have a very good combination of size and athleticism, so I agree with you, to an extent. Obviously though, you have to end up stopping the shots. I think to be a real top prospect for a draft as a goalie (so the level of prior goalies like Knight, Askarov, Wallstedt in recent drafts), you have to match the physical tools and the production. He might have the physical tools, but I think the production is lacking for now.
Could he end up combining them eventually? Sure, he's still young, but I think the early prognostications should be taking into account that the production isn't really there and that's taken him off that top prospect track as a goalie that some suggested he was on.