Think of it as an anti-spring-coming-up-through-the-floor-plate. These vehicles had the large transverse spring connecting the buffer shanks and the drawhook.
The spring is under compression when at rest & removing it without proper tools is a very dubious proposition (been there, done that, got away with it, never again).
The plate is only 1/4" thick, so how much protection it actually provided is moot.
Pete S.