My answer to that would be, "what makes him an NBA PG?". I guess I have more of an issue with comparing him to guys like Lonzo and Giddey....forget about positions. It's one thing to say "this guy is a PG because he is great at the things PG do" and another to say "this guy is a PG because a PG doesn't have to do these things". Lonzo and Giddey are high level passers and fit into the first group, Black is not that level of prospect IMO. I think his ball handling and passing are decent for a guy who is 6'7, but if he was 6'1 I wouldn't think of him as a great PG prospect based on his PG skills. He is impressive when compared to other 6'7 guys, but not necessarily impressive to all PG prospects.
Positions are just a label and don't matter at the end of the day. IMO, comparing him to Lonzo/Giddey in terms of being a PG is like comparing his shooting to Bane/Huerter or some other high level shooter. I have similar skepticisms about his PG/lead ball handler skills as I do with his shooting. Black's shooting is not terrible and his traditional PG skills aren't either, but it's no guarantee he becomes NBA level in either area. You could argue his traditional PG skills are ahead of his shooting, but the point still stands. I think it's unfair to compare him to guys are truly high level because they happen to be the same size. It's kinda like when people kept comparing Ivey to Ja last year. They just completely ignored the fact that Ja was an elite playmaker from the get go and Ivey was nothing close to that.
Caruso and Beverley are PGs....but so are Conley and FVV and also Kevin Porter JR and Dinwiddie. The label means very little, and you can better define a players position by what they do and don't. If Black is your PG, you're likely going to need a super usage/lead ball handler elsewhere. In other words, if he's your PG you need someone else to do a lot of the PG stuff. You'd be just as accurate calling him a wing.