I don't think this is needed, there already is a big red warning when someone hits the Viscount, so he can be warned/stopped/polled/kicked/banned/something, and sometimes, when a map is bugged (Desert Ruins or something like this name, where bots can get stuck behind a fence and without ranged its impossible to reach him), you just NEED to kill him.
And sometimes you do hit the viscount while trying to save him, after a while it could stack up reports and cause annoying situations. Unless the counter would get reset every round, it would be more of a problem than help.