Possibly being thick but if there is any issue that a bag on board is a danger to flight safety why was it loaded in the first place? My understanding is that all hold baggage is screened to a DFT standard and the fact that the owner isn't on board is in itself not a safety risk.
The lesson learned in the USA as the chap above aludes to, is that the TSA screens all hold baggage and it is therefore safe to send it ahead of me if I miss my connection.