Too bad they are wrong.
I finally looked up what Bibi actually said, speaking to conference for French-speaking Likud activists.
Here it is, in two parts:
“I went to Paris not just as the prime minister of Israel but as a representative of the entire Jewish people.”
Notice he didn't say as the representative of the entire Jewish people, but as a representative. This means that if he would have sent one of the Chief Rabbis or President Rivlin, then they would have represented the Jewish people as the official representative of the Jewish state. This is not offensive nor unreasonable. A representative is not the same thing as a leader. When the vice president goes to a funeral overseas, he represents the United States - he doesn't claim to be the leader.
The second part:
“Just as I went to Paris, so I will go anyplace I’m invited to convey the Israeli position against those who want to kill us. Those who want to kill us are, first and foremost, any Iranian regime that says outright it plans to destroy us. I will not hesitate to say what’s needed to warn against this danger, and prevent it.”Not the "Jewish position" but the "Israeli position."
In other words, Bibi says he will go anywhere he is invited to represent Israelis. Yes, he conflated the two trips while there is not a direct comparison between the two, but it still doesn't mean that Netanyahu claimed to be the leader of all Jews. He said he is a representative of all Jews and the leader of Israel. Both those statements are 100% accurate.
Those who are afflicted with Bibi Derangement Syndrome don't actually care about accuracy. Haaretz' headline for this article was "Netanyahu: I will go to Congress like I went to Paris – to speak for all Jews."
And most people read only the headline.