This is a much better reason to not allow some guys (e.g. Moore) to commit. If some guys are going to be late bloomers, our geography gives us the advantage to identify and grab them. Height requirements are foolish. "Be the best prospect" requirements make a ton of sense.
I don't believe there really are any specific height requirements, it just so happens that most of the WR's that would be taken ahead of E Moore are also taller than him.
Quite frankly, the height discussion doesn't make any sense, mainly because taller WR doesn't mean better WR, but being 6'0+ while also having good speed, good hands & route running is all apart of what makes a prospect good/great.
There are things Thornton/Austin(etc) can do that Moore (or others his size) can't do, just as there are things the smaller WR's can do that the bigger guys could struggle with.
Idk when Moore became Odell Beckham Jr lol, but there's legitimate reasons why he's not a take right now, his height isn't necessarily the main reason, but it does factor in.