I agree it's an old trick and one that you just cant get away with these days. Quite rightly heftier punishments are being dished out but even these fall short against what is both a dangerous and disruptive stunt.
Without going into too much detail, for obvious security reasons, I have been trained in assessing and reacting to bomb threats. There are many factors put together when looking at threats but if you turn up late for a flight with a warning against it expect to be met by the authorities. It happens too often to be ignored that late pax are responsible for the threats. Obviously if you are just geniuinely late then you have nothing to worry about. But if for one split second you have a moment of stupidness and even think about pulling this one . DONT.