That would have made more sense in V. Espcially if Vice City is set in the 80s. Zero would be either a baby or not born yet.
But remember CJ bought Zero's RC Shop, so it was likely expanded into GTA 6. Zero's RC Shop could possibly be managed by Rickie Lukens now. VictorVance1239 could buy a RC Helicopter and I could steal a Merryweather/Military Drone, for a GTA 6 Heist's setup! Everyones satisfied now!
But remember all of that took place in 1992 so it wouldn't matter if the game is set in the 1980s.