What evidence is Chomsky alluding to when he states the US is preventing a settlement between Israel & Palestine?

Chomsky book Fateful Triangle - The United Staes, Israel & Palestine was published in 1983, and republished in 1999 incorporating then new material on developments such as the Palestinian uprising, Israeli invasion of Lebanon and the ongoing peace process, and with a new foreword by the American-Palestinian Scholar & activist Edward Said, he writes:

Fateful Triangle may be the most ambitious book ever attempted on the conflict between Zionism and the Palestinians viewed as centrally involving the United States. It is a dogged exposé of human corruption, greed, and intellectual dishonesty. It is also a great and important book, which must be read by anyone concerned with public affairs. The facts are there to be recognized for Chomsky, although no one else has ever recognized them so systematically. His mainly Israeli and U.S. sources are staggeringly complete, and he is capable of registering contradictions, distinctions, and lapses which occur between them.

This would appear to be the book by Chomsky that details the allegations & accusations that he makes. Said goes on to say:

Chomsky commands what he calls “reality”—facts—over a breathtaking range. Fateful Triangle can be read as a protracted war between fact and a series of myths—Israeli democracy, Israeli purity of arms, the benign occupation, no racism against Arabs in Israel, Palestinian terrorism, peace for Galilee. Having rehearsed the “official” narrative, he then blows it away with vast amounts of counter-evidence

This is a matter of dismantling official propanganda and spin - functions of any state - but it doesn't allude to the central claim in the OPs question about the US opposition to a settlement. However he adds:

Chomsky’s major claim is that Israel and the United States—especially the latter—are rejectionists opposed to peace, whereas the Arabs, including the PLO, have for years been trying to accommodate themselves to the reality of Israel.

Said also adds:

Nor is Chomsky especially gentle to the PLO, whose “self-destructiveness” and “suicidal character” he criticizes. The Arab regimes, he says, are not “decent,” and, he might have added, not popular either.

In 1974 the PLO adopted what is called "The Ten Point Program". It is a program that outlines a phased plan for liberating all of Palestine. Liberating here means liberating it from Israeli rule. Obviously once all of Palestine has been liberated that means there is no Israel at all.

If we take this at face value, that means that any compromise you make with PLO, and therefore any settlement you make with them, will just mean you gave concessions for no reason, because they will later break the deal and continue the war to try to liberate the rest of Palestine.

Although the Ten Point Program is still in official effect within PLO, in 1993, Arafat seemed to contradict it in a press-release saying that "the PLO recognizes the right of the State of Israel to exist in peace and security". ref

But up to 1989, the publication of the book mention in the question, no such statement had been done, and the official policy of PLO was still that the state of Israel had to cease existing.

In light of this, blaming the United States for the lack of settlements is complete and utter Chomsky-style nonsense. It may be that the United States did not want a settlement, but Chomsky provides no evidence of that, and the main reason there was no settlement up to 1993 was that PLO's official policy prevented settlements.

This does of course not mean the US wanted peace in 1989, but Chomsky claims that it is the United States that prevents peace as a part of his general anti-Israel and anti-US agenda, not based on any actual evidence.