"The fact that Congress has to pass a resolution saying that anti-Zionism and antisemitism are the same thing means that people's efforts to end the conflation of the two are getting somewhere."
I think the point they were making was that it's not the liberals who are typically pushing that narrative.
Liberals tend to be against regimes which displace millions of people.
It's the liberals who are trying to illustrate that you can be critical of an authoritarian state, while understanding that the people living under that authority aren't responsible.
Who do you call liberals ? Is Biden a liberal ? Do you feel he is unsupportive of Israel massacres, promoted by extereme right government ? Do you feel being critical with Israel is OK and you won't be call antisemitic ?
(Disclaimer : speaking from France, where the exact same craziness happens...)
What is progressive and what is conservative is dynamic.
What is considered progressive now will be conservative in 100 years.
What is considered conservative in the West is considered progressive in the Middle East.
When people talk about Biden being Liberal, they don't mean in terms of a complete matrix of historical political figures, they mean within the context of the American political landscape.
In any case it doesn't matter, the point was whether Liberals are the ones making these claims. Painting with the broadest possible strokes, and narrowing it down to Liberals vs. Conservatives; Liberals are not the ones making these claims.
Liberals are very much anti-zonist; they hate how the Palestinians have been treated by the authoritarian Israeli regime, and also hate when Jewish people are discriminated against because of assumed pro-zionist stances.
Liberals want to support Palestinians who denounce Hamas, and Israelis who denounce Zionist philosophies.