This sounds like a wonderful idea, but I see a big problem with it. If we had such a feature some sysops would be tempted to use it as punishment against some bad users. There's a certain amount of 'vigilantism' that I've grumpily tolerated because it's very minor and the people usually "deserve it" in some sense. But this would open a huge new can of worms.
What about something that'd require multiple sysop approval? Like, 5 sysops to check something & click to confirm? Even if it's harder to do, it sounds really more 'safe', as finding 5 sysops willingly 'punishing' a user with this feature seems hard. Also, there could be a strict policy on that: any sysop using this against anything but a spambot gets unsysop right away (of course, i assume a sysop doing this would in any case lose some respect from his community).
Nicolas 'Ryo'