They claim to be anti Zionist and it sounds like their leaders oppose the occupation, support icj case, and support equal rights for all. https://tribunemag.co.uk/2024/11/anti-zionist-israeli-mp-i-will-never-surrender
If the psl as an anti imperialist party can exist in the US the imperial core, it would make sense that an anti-zionist party could exist even in a state built on Zionism. There were Jewish people there even before the British occupation, let alone it's recognition by the UN.
It sounds like they made a tactical choice to use their privilege to leverage whatever political power they can get to stop the oppression.