Is it permissible for me to take the money and dispose of it if someone swore not to give me money, then gave it to me without expiating his oath?

There is no blame upon you for accepting the money and disposing of it, so long as the donor is legally competent to dispose of wealth and is of good will. It is not forbidden for you to accept it on the pretext that the donor has not paid the expiation for an oath (kaffarat al-yameen), for this expiation is tied to his own responsibility. He should be advised and reminded of it.