How should Umar's statement regarding the gift (Nihla) of a father to his son be interpreted?

Primary text

Umar's statement prohibits the subterfuge where a father declares a gift (nihla) to his son, withholding it until his death so the son inherits it by virtue of that declared gift. If the son dies first, the father retains it, circumventing inheritance rules. This specific arrangement is prohibited, commanding that the son must take possession (hawz) during the father's life, so that if the father dies, it is inherited as part of the son's general estate. This ruling pertains specifically to the gift from a father to a son.