This cannot be a good time for US foreign policy. They now have to choose between the lesser of two evils. If they leave Palestine to its own devices, the Hamas-majority Legislature may just prove very good at fund-raising and ultimately slip farther away from US control, however tenuous it may be today.
On the other hand, the US may continue to fund that government, essentially giving money to a bunch of thugs hell-bent on spreading anarchy and violence worldwide and the US will become the dubious backer of a terrorist state.
But is this really that strange? The US, for years, gave enough money and firepower to Saddam's Iraq to wage a war with Iran. The US, in the Great Game against the former USSR, gave enough money and firepower to dozens of Third World dictators to thwart whatever latent Socialist and Communist tendencies that may have existed.
Therefore, the US should not feel shy about funding a Hamas-dominated Palestine. It will be in line with what they have done for decades. They cannot simply walk away from their legacy or wish it away from their psyche. This is what the US does. So, let us let them get on with it!