Here's why:

* Radioactivity: Polonium is highly radioactive. Its atoms decay quickly, releasing energy and causing structural changes. This inherent instability makes it impossible to shape it like metals like gold or copper.

* Limited availability: Polonium is extremely rare and highly radioactive. Handling it is dangerous due to the risk of radiation exposure. This makes it impractical to study its malleability in the same way we would for other metals.

Therefore, while it might be possible to technically deform polonium to a small degree, its extreme brittleness and radioactivity make it essentially impossible to manipulate in the way we normally think of malleability.