Now if you're going with periodic checks then let's assume that it has crashed, it's own thread crashed silently. It doesn't send "heart pulse" signal to server, so server after a period of defined timeout kicks the player out and bans. Ouch? That's why I said that stability is paramount and so I wouldn't put my trust as quickly. But without periodic checks it becomes all to vulnerable.
Thing is that I think it will likely not stop people who know how and what, but will put unnecessary load on players that have nothing to do with it. Ironically seems to be quite common to those intrusive protection mechanisms relying on client-side proxies.
