Rabiot, currently away with France at the World Cup, has admitted he is considering his future in Turin.
Legrottaglie said: "He is a strong player. To say that he has grown is fine, but his characteristics have long been known. Difficult to find one with that foot and strength to make the difference and is irreplaceable even in a strong team like France.
"He is immovable because he has important characteristics. Juve would do well not to give him away, because he can give a big hand both in the construction phase and in the insertion.
"He has vision, he knows how to filter the balls well, he needs a midfield to help him with his characteristics."