Roger - the problem is that you have to stop the SAR aircaft searching in order to investigate anything the UAV 'sees' which might prevent the helicopter locating the actual target. For every time this happens, you have lost your 'force enabler/multiplier.
Things like clothes found on a beach normally require detective work by the crew along with the CG and police - a UAV can't land on and ask a member of the public if they have seen anything.
You are not going to improve the quality or effectiveness of searches by using UAVs but you might reduce the cost and tick some 'area searched' boxes which could keep the beancounters happy.
Are the UAVs going to rely solely on AI or will there need to be a human operator staring for hours at the downlinked images as well?