*sighs* I hate generalizing, because it serves no useful purpose and only shows ignorance. Freakin' A, such is life.
That is a stupid thing to say when it comes to politics.
Designations like "liberal" and "conservative" are based on common opinions held by the members of those groups. The entire American election system works on the basis that there are, in general, two different opinions competing.
And the pro-Arab-imperialist position is indeed a common trait among the left.
Heck, the German socialists even have a group among their own dedicated to fighting the latent and open anti-Semitism among German socialists:
So while it is true that not ALL left-wingers are anti-Semites, it is certainly a problem that so many are. And while you attempt to solve that problem by opposing generalisations (and hence focussing on the exceptions), this left-wing group (who are a part of the German Socialist party) focus on the other part of the problem, the non-exceptions, the GENERAL left-winger.
Here is an English-language article written by the spokesman of the BAK Shalom:
Luckily their attitude towards generalisations was also one of hatred. But they didn't hate that it was pointed out, but the fact that there was something to point out.
We spoke about this before. How many liberal protesters do you see on the streets demanding that Arab countries end slavery or allow for homosexuals to marry? Well, there are lots of liberal protesters on the street protesting the "occupation" or even the existence of Israel.
When it comes to Israel, many liberals forget the values they claim to believe in. Arab nationalism, for liberals, outweighs all liberal values. That is a generalisation. But it is also a problem for liberalism.