To be honest, I don't think the effect would be worth the hassle.
It is mostly ignored when non-regular players death evade; regulars do it pretty rarely. And regulars mostly do it by quitting the game and pretending that they've got connection/computer problems or a hamster which enjoys running on the keyboard and accidentally typing /q with its little paws. The system that you suggest, Ege, would be also easy to avoid, you just need to run for N seconds without taking damage and then type /rc, which is more than possible, especially on city maps. It would be probably more effective to check if there are enemies in some vicinity around you, but, again, it's not that hard to run away, and if the radius is too big, the whole map would be single 'danger zone', especially for civilians.
So I think that there is no need to overcomplicate the system with such scripts. The best countermeasure against death evaders is a video and an IRC log or at least a screenshots with clear timestamp and your position supplemented with IRC line with the reason of disconnection, player's position and HP and armour.
-1.