The murmuring around town in San Diego suspects a tip off to the Taliban by one of the parties we are training...perhaps even a suicide bomber aboard the chopper. It was a night operation. Hitting the chopper with an RPG would have been a lucky shot. The local SEALs were told to “shut up”. That isn’t going over well.
SOF guys will combat it by taking away the cell phones and isolating the host nation troops before an operation, but it only does so much. The targeting process involves notifying Afghan officials when a raid is taking place, and those guys bleed information like OPSEC hemophiliacs.
Suicide bomber on the chopper is speculation, and not good speculation. It would be smarter for a bomber to blow up at altitude than near the ground where there might be survivors. The Taliban wouldn't claim, and we wouldn't confirm, a 'shoot down' in that case. Yeah, we can't trust the guys we work with, but OPSEC violations leading to ambushes are far, far more common than inside suicide agents. Plus, it sounds like this bird was on the return trip.
As far as being told to 'shut up', these days, every unit in the military gets gag orders when there's a catastrophic event. Facebook and email blackouts, no phones, etc. All that means in 2011 is that someone in the unit died.
I don't discount at all that some OPSEC violation led to the Taliban having some RPGs ready. That happens all the time. RPGs kill helicopters, so if you put enough in the air, sooner or later one's going to connect.