Hardy is 6'3''. Either he's a PG, or he's an undersized SG.
These are the listed heights of our guards
Fox: 6'3''
Huerter: 6'7''
Davion: 6'
Monk: 6'3''
Keon: 6'5''
Duarte: 6'5''
Kessler: 6'8''
Jones: 6'6''
Except Davion, whom we mostly want to play the backup PG position, everyone else is the same height or taller than Jaden. Some of the folks in the above list will see some time at 3 (most likely Kessler and Huerter, and maybe Jones if sees any time this year). Barring Monk though, all our SGs are taller than Jaden, and Monk has good handle/creation skills for an SG.
We already have a problem with Davion, since we are forced to have him guard taller players. As for getting the glut of two guards, should Monte have relied on the growth of a second round rookie pick over proven players? You actually answer the question yourself when you say that he would be stuck in the G league.
Look, we all want the team to hit on every draft pick, including second rounders, and undrafted FAs. Rarely happens though. Teams like Dallas, or last year Lakers are often almost the perfect spot for such players. Both teams decimated themselves of role players in order to get stars. This opens up opportunities for players, and if they and the team are lucky, they both gain.
Till a significantly improved Fox showed up last year, we had only one star in Domas. Our team was built around depth, and we all hoped would somehow sneak into the PO, possibly via the playins (honestly, that's what I was hoping). Late FRPs, second rounders usually don't see much time on these teams. Even if we had picked and kept Hardy (or Prosper this year), they wouldn't have seen much time.