Arguably, why should there need to be a literal option to switch this? Can't the game just recognise there is no controller plugged in and switch to K&M prompts itself? Do PS5 and Xbox users need to switch to their respective controllers too?
I agree, it should do this automatically to be fair. It shouldnt require you to go in and manually do it. On the flip side of that, if you are a professional reviewer and doing a professional review, you would think that as an experienced game reviewer you would at the very least, check in the settings. He actually did the exact same thing in Total Warhammer 3 where he complained that his units just stood still from time to time after fighting, without actually understanding that they did so because he had them set on Guard Mode. Such oversights are fine for a run of the mill gamer but not for a professional reviewer. That however does not of course excuse the fact that the input detection really ought to be automatic.