Horowitz is the exception, Eistein the rule. I would also add, though, that following WWII I would think that many Jews could be forgiven (to a degree) for embracing socialism. I would, however, be proud had they embraced republicanism instead.
It is my understanding that Einstein never repudiated socialism.
Einstein, while one of the five or ten greatest physicists who ever lived, was a monstrous human being. He fathered an illegitimate daughter by Mileva Maric in 1902, but forced her to give the child up for adoption. He later married Mileva, then abandoned her [the feminists believe he stole her work as well, though I'm dubious] in favor of his cousin, the divorcée Elsa Loewenthal [with whom he had had a lengthy affair during his marriage to Mileva]. He is remembered as a steely cold, even hateful husband [I treat my wife as an employee whom I cannot fire], and as a ruthless adulterer, whose children's lifelong health problems are suspected to stem from his own syphilis. In politics, he was a recalcitrant stalinist, with membership in more than 30 marxist organizations, many of which explicitly advocated the violent overthrow of the United States. After the second war, he carried on a treasonous affair with the adulteress Margarita Konenkova, herself a spy for the Soviet Union. The fact that he is remembered with any fondness whatsoever is a tribute to the extraordinary power of good marketing and a friendly press. Some links:
Einstein's Daughter: The Search for LieserlThe Chinese hate him because he didn't charge them to sleep in the Lincoln bedroom.
Early Letters
The Letters to Margarita Konenkova
Why Socialism?
FOIA Release of FBI Surveillance Documents
Seriously, though: They ought to treasure him as a marxist icon. The reason they don't has a lot to do with the Sino-Fascism that John Derbyshire has catalogued so eloquently.