I'd be more worried about it going off when you "crash" normally..
They've been in cars long enough that it probably isn't a big issue anymore, but having this thing go off when you lay down your bike would really suck.
Just like in a car, the airbag deployment sensor will use accelerometers to determine whether the airbag should be set off. Laying the bike down won't deploy the airbag unless it comes to a sudden stop, like skidding into a telephone pole or something.