If Guthrie has been vacinnated x 2 is he not allowed to play? Horsfall should play imo. Ete too! For Gawd sake JB play Pollock if only to appease his fans. Above all play Kioki in midfield!
Even if he has been vaccinated x 2 he would be unlikely to be fit and well enough to play Tuesday if he wasn't able to play Saturday, it's not just about isolation, it's also about how bad it affects you. Hopefully for his sake and ours he is not feeling too bad.
In any case even if he was fit and raring to go I wouldn't play either him or Horsfall in that match, they are too important to the team to risk an injury in a cup that very few care about.