Good lord. Indeed, the extent to which the "hero" is kind of unhinged is totally consistent with fairly-normal isekai protagonist behaviour... To be fair: Not totally unreasonable so far for someone who's been transplanted suddenly from a peaceful modern world, into a war-torn one that doesn't quite feel real, and for whom it probably feels like it's supposed to all work out like something from Shounen Jump or something still.
Just that here we have a relatively calm, reasonably cynical adult looking at it and going, "Oh, shit. ...This is not going to end well."