First, what catastrophic damage??? The engine can be turned in reverse just as in forward without damage. Kind of unnerving as the engine will make strange noises but that's just air. Suppose you might be able to cause problems with valve timing with a chain driven cam If the chain tensioner didn't work but you'd have to get the engine turning over pretty fast to do it. Back in the good old days of handcranking petrol engines with spark retard mechanisms, sometimes they would actually start and run in reverse, though poorly.
Second, doubt very highly that you could ever get a diesel
to turn over from water
force on the prop with the transmission
in reverse. Used to hand crank my MD2b
by popping the compression
releases. Even at 4 knots or more with the transmission
in forward, the engine wouldn't turn over by itself with the compression
released. Did make it easier to crank, however.