You're using Leftist logic to try to make it sound hypocritical. If Jews are accused of lying all the time, we inherently know it would be for their benefit, not their detriment. If a Jew speaks up to say something negative instead, who would lie to cause themselves harm instead of benefit themselves?

When Thomas Sewell talks about problems in the black community with fatherlessness, crime, and anti-Whitism, even the most ardent Uncle Ruckus will point at him and say "see, he's trying to tell you what I would be called horrible for saying." It's not a double-standard, it's using an "inside source" that can't be so easily dismissed out of hand since it's assumed they would have no reason to lie just to hurt themselves.