In the US response to the vote, the argument was essentially "this cannot lead to any substantial change and only serves to reafirm statements already agreed upon previously and notably in the universal declaration of human rights".
Agree with the assertion or not, or think there's some other motivation, but that's the argument being made.
The UN doesn't vote on single statements. If I have the right document, because there are several times the UN has voted in "everyone has a right to food", it's 53 statements.
Encourages all States to take steps, with a view to progressively achieving
the full realization of the right to food, including steps to promote the conditions for
everyone to be free from hunger and, as soon as possible, to enjoy fully the right to
food, and to create and adopt national plans to combat hunger;
Isn't quite the same as the title of the map, which is closer to what's in the universal declaration of human rights which the US did sign.
Everyone has the right to a standard of living adequate for the health and
well-being of himself and of his family, including food, clothing, housing
and medical care and necessary social services, and the right to security
in the event of unemployment, sickness, disability, widowhood, old age or
other lack of livelihood in circumstances beyond his control.