I think Pop is fine with playing rookies,- so long as they go through a full training camp and preseason plus if there is a role that needs filling.
Kawhi filled the backup SF spot, and Blair ate up minutes at PF (pun intended

). Splitter, had he not been IU injured early on during his rookie year probably would've been a rotation player and the Spurs might've beaten Memphis that year.
Spurs still have good guard-wing depth, so Walker probably won't play much, unless of injury. He should still get a lot more minutes than White did, but that was still super odd for Pop to not play one of the more polished Spurs rookies , almost at all last season.