Pep Guardiola wasn't the one in charge of the match, it was his assistant coach "Juan Manuel'' who was in charge of the match(supervised, featured, and made the substitution in the match). This is his first time being in charge of a Manchester City match wouldn't blame him that much since Pep Guardiola went for a back surgery at Barcelona. Although the back surgery has been done successfully.
Even if Pep Guardiola is not present, if he is in bed and recovering, technology makes it possible for him to still pass instructions to the assistant coach while watching the game from the hospital where he is in recovery. Knowing how much Pep loves the game and really wants to maintain his brilliant record, I do not think that he will be able to sit, and watch Manchester City play without making contributions to the team. Manchester city almost drew their game today, but Rodri came through again.