The Ran writes that this is a refutation to the Rambam’s opinion, who holds that one who forbids another person benefit from himself and then feeds him will incur lashes because he has violated the transgression of “he shall not desecrate his word.”
The meaning of the Ra”n seems to be that if the Rambam is correct that if the vower provides the forbidden item to the other fellow, he has desecrated his word; then, the giver may be guilty of me’ilah as well! Why does our Gemora assume as an obvious point that the giver has not committed me’ilah?
The Machaneh Efraim (35) and the Lechem Mishna answer that although it might be prohibited for the vower to give the other fellow the forbidden item, but that does not mean that he has committed me’ilah. He has desecrated his word, but he is not guilty of me’ilah, for it was not regarded as hekdesh for him.
Reb Shlomo Zalman Auerbach explains that the Ran’s proof was from the language of the Gemora. The Gemora stated unequivocally that there can be no prohibition on the giver, for the loaf is not forbidden to him. It would seem from the Gemora that there is no prohibition on the giver at all! This is not correct according to the Rambam.