There is a fine line between wryly commenting on racism by displaying it in humor, anmd reinforcing racist beliefs in a humorous way. "All in the Family" was the class ic example. The point was to depict Archie Bunker as racist and wrong, by showing how stupid his racism was. It was pretty well known that many people, however, liked the show (and Archie) because they basically agreed with him.
Dave Chappelle stopped his show because he was afraid that he was crossing the line between ironically making fun of racism (by depicting characters who were racist or minorities who fit racist stereotypes) and simply validating racist beliefs, and felt pressured to go more in the direction of the latter, because the audience responded to it.
Silverman is in the same tough spot, though, to me, she actually seems like she probably is racist in a number of ways. Maybe she is not and I am just completely convinced by her schtick, but I can't see that she's striving for "irony" most of the time, in the way Chappelle clearly was.
On her making fun of Jews, I assume that is ironic. It would be unusual (though not impossible) for her to be an anti-semetic jew). so I give her the benefit of the doubt. Her anti-jewish material I assume is not really intended to be anti-jewish. Her anti-asian material (which she hits pretty heavily) I am less sure about.
It's also why I completely understand why whites can't use the n-word and blacks can. It's highly unlikely that blacks intend the word to be disparaging of their own race, in toto. It's very much more likely that a white person using it means it in that way. As such, it is not that there is a double standard, but rather a single "don't disparage a whole race" standard that blacks can be deemed to more easily meet than whites in relation to that word.