My assumption is that if the Seat Occupancy Detector (OC-3 Mat) is coded out, the MRS5 module will behave as though the sensor is faulty and assume that the passenger seat is occupied and activate the restraint systems. Otherwise, the indicator for front passenger airbag deactivation would be lit. If that is in fact the case, the front passenger seat would no longer be safe for a small child in a child restraint system.
I also believe that the seat belt tensioner is activated as long as the seat belt is fastened. Of course, all of this is speculative as the US MRS system differs from the rest of the world due to NHTSA regulations making it difficult to determine the exact functionality without a crash test dummy...caveat emptor!
MRS5 Manual
http://workshop-manuals.com/bmw/3_se...e92/page_4511/
http://beta.askatech.com/AskATechLiv...er.ashx?a=2316