I in all honesty I fail to see how the occasional glance in mirrors would have prevented this poor motorcyclist getting walloped. Who was to say the Truck driver wasn't being a smart ass and looking to brake at the last minute?
I hate waiting at lights with no car stopped behind me,I always have the bike in neutral and do glance at my mirrors until someone has stopped behind me, until they do I pull the front brake lever to activate the brake light as a warning. Some of you guys with the later SV's could flick your hazards on in these situations as a bit of a precaution maybe?