Sucharov's essay can be read here. You can watch the video of her debate with Max Blumenthal at CPAC or read my transcription of it here.
"They heard the gentle remonstrance of a kindly king with an erring but
much-loved minister." -- J.R.R. Tolkien
The responsibility of liberal Zionists is not just to defend Zionism from anti-Zionists but to police its own excess, and honestly admit its failings. This is what you are asking of anti-Zionists. It's fair to assume you ought to practice it yourself. Take one example from the debate, the right of return. It may be unrealistic and therefore unfair (as Noam Chomsky has pointed out) to tempt Palestinians with the right of return but just on an academic note, if Israel is to return to Zionist ideals, it would have to return the property it took from Palestinians. Theodor Herzl said if Arabs refused to give up their property you should simply build where you face no objection.
Another thing liberal Zionists must face in order to be taken seriously, however uncomfortable it may be, is Israel already is an apartheid state (EDIT 8/1/2014: or ready to become one). Between 1949 and 1959 the Afrikaner government passed the the Prohibition of Mixed Marriages Act (1949), Suppression of Communism Act (1950), The Prevention of Illegal Squatting Act (1951), The Riotous Assemblies Act (1956), and the Promotion of Bantu Self-government Act (1959). These all are parallel with proposed and many enacted laws in Israel including banning of Arab parties in the last 20 years, mostly under the governments by the current ruling party Likud. None of these do you mention by name, either in the debate or in this essay. It was notably Max Blumenthal, the "anti-Zionist," who brought up the Bedouins facing eviction, not you. I think this is because it does not fit your endgame. This is a sign of degrading democracy, not a sign of hope or a defect in Israel. So you find it hard to face it.
It is also a feature of the society, not an accident. Israel has brought itself into this situation by creating a country of Western ideals (including the nation-state and the Fascism it entails) and Western trade interest, as Theodor Herzl intended. By aligning itself with the US, its main military supplier, as well as many dictators and opressive governments in the region, as well as Latin America, the idea that Israel means well loses credibility. We should also remember that in US history, the pretext of the war on terrorism overtook the pretext of communism specifically in relation to South Africa. When Reagan was in office he was advised to make a distinction between "authoritarian" and "totalitarian" governments and attacked, with undemocratic support, the helpless Latinos in his way under the pretext Israel's military hides behind today. This policy also included support of apartheid South Africa and the peaceful yet illegal annexation of Western Sahara by King Hussein II of Morocco. These are crimes concealed by nationalist fervor and a totally biased vocabulary (read the speeches of Hussein if you doubt me). That a state can be a benevolent force is an illusion, which is the point.
So what must be countered in Israel is not just specific laws. What should be discouraged is superstitious coveting of the power and credibility of nationhood, and the propaganda you write in its defense. Israelis and Zionists naturally recognize this about Iran and Gaza, but not themselves. While it may not be necessary to abolish it -- Leftists do not support violent overthrow of Iran for example -- we certainly shouldn't encourage their propaganda either. For whatever reason, I don't know exactly the cause (human nature perhaps), the ability to make historical analogies is limited by the so called liberal Zionists to countries like Finland and Canada.
But the important history here is the US', Israel's main supporter. When the US oppressed the "Indians" we heard what we wanted: "Come over and help us." This goes right through American history, notably Vietnam which we wanted "spared" from the scourge of communism, and Iraq which we "liberated" into a country of sectarian warfare, its oil sold to the highest bidder. You hear this pop up in relation to the "myth" that Palestinian water is under Israeli control, and the crocodile tears shed for the women living under the government of the Hamas party. This mentality is also repsonsible for domestic and military pressure in Israel that is preventing the two state solution, a major step in resolving the conflict. Even if Arabs tomorrow went on TV and renounced terrorism, we would not see peace. Al-Jazeera reporter Clayton Swisher reports that Bill Clinton "falsely told the world that Arafat had rejected his parameters" out of fear of upsetting internal Israeli politics. That's not about laws, it's about political demographics which would be made impossible with a stronger check on military excess and Zionist nationalism. Israel currently has sitting in a jail cell a popular Palestinian politician who supports the two state solution. He is imprisoned thanks to the myth created in the wake of Kissinger's bad faith UN negotiations that Israel's security should be equally weighed with the national borders. He was tried in a military court in occupied West Bank for signing checks to "terrorists" -- namely Palestinian militants who have resisted the Israeli soldiers and need money for lawyers.
Even putting propaganda aside and going to concrete proposals, this is not contradicted by the two-state solution simply because it has Arab support. Mondoweiss writer Phan Nguyen pointed out we should remember that during apartheid in South Africa there were two-state solutions proposed (this was Abraham Lincoln's idea as well for African-Americans). It may be the best of the rotten ideas around but it does not mean apartheid doesn't exist. Rather, as US and South Africa illustrate, it is an idea very compatible with apartheid and an out of control state (remember, Lincoln also suspended Habeus Corpus). Much like other instances of US power and US involved powers, we understate the evils of the Israeli strategy. The rest is a red herring.