Easily KK. He isn't even part of the RHP lineup. He only starts against high-velo (95+) righties specifically because both Biggio and Schneider struggle with that, and in ballparks like Camden Yards where they want the extra defense in LF with Varsho instead of Whit. The RHP lineup was the one we saw on Thursday against Baltimore when they were desperate for some offense after the stinker the night before. Prior to this game, Varsho/KK had started every other game at Camden Yards this season in LF/CF:
LF Whit
SS Bo
DH Belt
1B Vlad
RF Springer
CF Varsho
3B Chapman
C Jansen/Kirk
2B Biggio
The most realistic way to get Schneider into this lineup almost everyday is if he just takes Biggio's spot at 2B, but reason why Biggio has been getting a lot more playing time against righties is because ever since he made some changes to his plate approach in mid-May, he has a 138 wRC+ vs RHP in 132 PA since then. On top of that he has a career 105 wRC+ vs RHP, so Schneider (John) up until this point has probably just been chickening out and deferring to Biggio's "consistent track record" over the possibility of what Davis could be with more consistent playing time.