It is the best time to do it.
Some on the left clearly struggle to separate Judaism and Israel, as several incidents have shown. Some high-profile, anti-Israel MPs have attacked Jewish people. It is the context that preceded this. It is a common occurrence on the left - people, angry with Israel, take it out on Jewish people.
It is the Labour leadership's responsibility to set boundaries, and I felt that it was Corbyn did. Some Jewish people, are pro-Israel, so some Jewish people will be upset with this. But the issue should be about confronting racism, not placating people with pro-Israel sentiment. It is not offensive to upset people for being pro-Israel, where it is to upset them for being Jewish.
Call it a comparison, I see it as an analogy, framing the debate in a language the left already understands. You wouldn't hold Muslims accountable for the actions of terrorists, so why hold Jews accountable for the actions of Israel? Basically don't let a group of people be tarred by the actions of the political extreme right.
For me, more worrying is that racism is hand-waved as a bad thing and it prompts people to hide their views rather than actually confront them. Ken Livingstone needs to be taught, not told to be quiet. IMO this is why the country has had such problems with racism in the last week. People didn't stop being racist, they just hid their views, and when those views were legitimised, the racism came back out into the open. As a country, we need to confront the issue of racism far more directly, and that means actually talking about it.