I don't know the answer.
Of course, there's no question about the moral aspect of the question: they should side with Ukraine against the barbarous Putin.
But there's also value in having a few potential mediators available. And Israel with its populations of Russian and Ukrainian Jews does occupy an interesting space. And Zelensky is himself Jewish, of course.
Which is more important, morality or utility? I dunno. There are so many questions of this sort where the alternative answers are assymetrical.