Short Point Guards as the lead offensive option rarely win championships, anyway.  Steph is the only one in the last 30+ years and that's arguably because he's the GOAT shooter.
That Simons can average 23ppg on a bad team and probably 17ppg on a good team would be a sign that you have depth and a variety of offensive options within your starting five.
The blueprint for most championship squads dictates as such - one MVP contending superstar (usually not a PG) and three All-Stars/borderline All-Stars helping them out (starters that can hit 17+ppg - though, one of those guys could be a defensive type like Ben Wallace or Draymond).  3/5 starters must play defense.
Most championships in history reflect that
In that sense, you keep Simons with the hopes that he comes off the bench as a sixth man or as a potential option if Scoot doesn't pan out.  Unless you get Ausar Thompson or Tari Eason back, trading him would probably be a waste.