I suspect that simply by looking at a list of conservative governments in the Americas, we already would have a fairly complete explanation.
- Conservative, because right-wing parties are naturally more aligned with Likud and with Israel in general, and often more militarily hawkish, whereas the centrist and left-wing consensus in most countries is strongly against the continuation of the war.
- And in the Americas, because (a) due to geographical factors, they have a lot to gain by going along with the USA position in important votes, and less to lose from opposing, say, the position of Russia and China, and (b) they do not have as much anti-Semitism to reckon with as with the far right in some other countries, particularly in Europe, which might provide a bit of an obstacle toward looking too pro-Israel.
Many of the other countries, such as Bolivia, Venezuela, Brazil, Mexico, and Canada, have leaders associated with left-wing parties, whether democratic or authoritarian. There are a bunch of more centrist leaders, too, as in Belize, Uruguay, or El Salvador.
Looking at the political landscape of the American continent, Guatemala and Paraguay currently are among the countries with the most right-wing leadership: although Javier Milei is probably the most right-wing leader in the Americas at the moment, he became president of Argentina right around the time of the UN vote, so there was probably not time to change the delegation.
