blocking a user without them knowing

i have a cooking blog, and i have this annoying silly man who keeps spamming my recipes with reaaaly bad cooking advice. i’m sure they’re trying to help, but they’re just plain stupid and i’m scared of having innocent inexperienced visitors actually do what this man is saying and wreck the whole dish!

i haven’t tried blocking him, because that would probably upset him and he might go after me on a personal vendetta (switching IPs and leaving troll remarks or whatver). is there a plugin that allows me to block his comments but display them so only he can see them and not suspect? a cool name for this plugin would be Talk-To-The-Hand…

thanks!