Its been more than a decade since I was an undergrad Materials Engineering student (I didn't even graduate in in that field), but I think the answer would be th

Its been more than a decade since I was an undergrad Materials Engineering student (I didn't even graduate in in that field), but I think the answer would be the same as for any coil. It is easy to elongate a compressed coil through deformation, but it is much harder to compress an elongated coil through deformation (while preserving the coil's properties...you can definitely smash one into a ball quite easily, but it no longer acts like a coil). With SMAs, there aren't two memories, there is a memory and a non-memory state. The non-memory state is like any other wire, deforming with physical force. In order for your proposal to work, you would have to take an elongated memory coil, and then physically deform it into a compressed coil to get the contracted state. That is a lot harder to do than to take an elongated coil and return it to a compressed memory state.