a piece of copper tubing i've seen before from an air conditioning unit could not be bent by hand
On the list of most malleable materials, copper is pretty up there. It's not like it's going to bend like aluminium, but a relatively thin copper tube isn't going to provide much resistance against pure manhandling, especially if it's heated up.
Of course it wouldn't be easy to just bend it by hand, that would defeat the purpose of material's use if it could just bend willy-nilly.