Objects can only be initially placed in clear terrain, and an object dropped due to loss of Super Strength or whatever (or placed or moved) into a square already containing an object is removed from the game.

But what about objects dropped (or placed or moved) into hindering terrain? I was informed in a game tonight that the object would be removed from the game as well. Is this correct?

Not at all, as far as I know.

Nope. Nothing prevents this...just like nothing prevents you from TKing objects on top of objects.

The rules specify exactly when the objects are removed. If it isn't one of those things, it stays in the game.