I'm sure you would say the same thing if I used the word DUCTILE or even the term PLASTIC DEFORMATION.
I could say use a magnet but then that would be negated by some types of stainless steel.
So where do you want to draw the line?
Malleable and ductile are
Synonyms. In fact I would have a problem if you said Zinc was ductile and steel was not. They are both malleable and ductile.
Mr. Dictionary is our friend. It keeps us from perpetuating incorrect terminology if we do not have the education to know the correct terms.