From the Standard Rules for Pushing It To (link is to 6M62’s, but this is unchanged in subsequent versions):
Check an actor pushing something to (this is the standard pushing in directions rule):
convert to special going-with-push action.
Check an actor pushing something to (this is the block pushing in directions rule):
if the actor is the player:
say "[The noun] [cannot] be pushed from place to place." (A);
stop the action.
The block pushing in directions rule is unreachable, right?
Maybe it’s a useful fallback if someone decides to drop the “convert to special” rule?
The index notes the following:
If the noun object has the either/or property ‘pushable between rooms’, then the action is converted to going by the ‘standard pushing in directions rule’. If that going action succeeds, then the original pushing it to action stops; it’s only if that fails that we run on into the ‘block pushing in directions rule’, which then puts an end to the matter.
So it’s a fallback for when the going action fails.
That doesn’t sound right to me. If you try to push something into a wall, the going action will fail (with a “can’t go that way” message), but you won’t see the block pushing in directions message. And RULES confirms the block pushing in directions rule isn’t run.