I'm not the OP, but allow me to share my mixed feelings.
I agree with the motion. But it's a vote loser. Voters are idiots and a not insignificant number will be convinced by the British press that this is anti-semitic, c.f. Jeremy Corbyn.
The Greens could have had all the right policies vis-a-vis arms sales, sanctions, BDS etc. without passing this motion, and for as long as they are a threat to Labour, that would have some weight in the public discourse. But I would be very surprised if passing this motion doesn't ensure that Polanski loses the by-election, and I fear that's going to begin a slide back into irrelevance for the Greens.