the easy answer is that it's for domestic consumption, but the polls don't really support that analysis. while there is a vocal and well-funded pro-palestinian minority that has very right-wing politics and masquerades as liberals on the fake left, the overwhelming majority of americans remain dominantly pro-israel and in support of a ground operation in rafah. dhimmi joe and his binkie are acting against popular opinion in the united states, and not with it.
rather, there are clear geo-political reasons why the united states would oppose the elimination of gaza as a buffer state between israel and egypt, as it could lead to instability in the region. there is a peace treaty between egypt and israel but it's more like a mutual non-intervention agreement. the israelis don't bomb egypt the way they bomb syria or lebanon. further, the murderous dictatorial regime in egypt (which biden did and does back) is not very stable, and some instability could lead to internal revolts. much has been made of the broken saudi-israeli detente, but the saudis are more likely to be concerned about losing their client in egypt to a rival, like the russians.
the americans are so frequently pro-israel that it masks the reality that the actual middle eastern policy is barbarian management via divide and conquer. america seeks to maintain a series of perpetual conflicts in the region, to prevent any single actor from becoming dominant. america's shifting allegiances have to do with ensuring that the fighting never ends and nobody ever wins. a final victory by israel over hamas would consequently be a red line for american geostrategic interests, as it ends a conflict that is supposed to bog down israel into perpetuity and prevent them from expanding outwards.
i think, however, that binkie is misreading the israelis. binkie needs to remember that the jewish state is not what it used to be; today, israel is a fundamentalist theocracy, like all of the other states in the region. while it remains a democracy, it may not be one for much longer and it no longer has the characteristics of a western democracy, which include axioms like the paramount nature of free speech. israel is on a course to become the mirror-reflection of iran.
as bizarre and naive as it sounds, what israel wants is really limited to the promised land. a normal country may want to take advantage of the situation and move settlers into their conquered territories, but israel has been clear about the point for a long time: biblical gaza is where the philistines lived, and was neither in the heretic/hedonistic kingdom of israel nor the divinely protected (until it wasn't) kingdom of judea. the attack on rafah may be vicious, and the israelis may decide to leave troops on the ground (who would argue they shouldn't, after the october attacks?), but there is no imminent threat to the balance of power because the israelis will actually draw their own boundaries as minimal rather than maximal.
the jews are weird. they always have been.
i'm consequently going to call for the resignation of linda thomas-greenfield, as allowing this resolution to pass was a substantive mistake and i'm going to call for binkie to resign as well, in an exercise of ministerial accountability.