It seems to me that if the belt breaks , even on an interference engine: the valves will slam shut . Maybe it 50/50 chance either way.

Belt has to be replaced any way
compression test on the cylinders.. tells you straight away
zero or low compression numbers ..valves bent

in an interference engine OHC or DOHC belt breaks
the cams stop dead and pistons continue to move up and down

non interference there is a gap between pistons and valves

No
your logic is flawed by your lack of knowledge of how and engine an cam shafts work
when the belt breaks , the camshaft stops turning and the valves that are opening , fully open or closing are all in that position from the cam lobes but the pistons keep going up and down from the vehicle movement driving the crank shaft
as the valve movement is in concert with the piston position to open and close when the piston is not near them, damage results when the valves cannot get clear of the piston as they are held in position by the cam lobes