A person appointed another to give away all his wealth in charity upon his death because his heirs are wealthy; is the agent required to carry out that bequest?

Question:
He says: Honorable Shaykh, may Allah grant you success. A wealthy man lived an unrighteous life and died from AIDS. Before his death, he appointed a man to give away all his wealth in charity because the heirs are wealthy, and he saw the need to make expiation for his sins, believing that this was greater than the heirs' need for his wealth. His question is: Is it permissible for the agent now to carry out this bequest and give the wealth in charity?

Answer:
No. The wealth is not his once death descends upon him, or rather, once he falls ill with the illness of death. He is then restricted, and the wealth is not his; it will pass to the heirs. He has no right to dispose of it except in the third. The Messenger of Allah (peace and blessings be upon him) granted him permission for the third or less only. The wealth belongs to the heirs. It is not his. Yes.