This is because Israel can't really just be resumed, on a geopolitical level, to the Palestinian conflict - like most countries, it's a complex country with a multi-faceted society, and complicated relations with the other (also complex) countries surrounding them; and in Israel's case specifically, those relations tend to be even more complicated than the average, due to their unique history in the region.

Also, it's not like Russian fascists genuinely care that much about the Palestinian cause; they're doing it mostly out of opportunism. It's like whenever they bring up the rights of Palestinians (or any other oppressed population, like Black people in America) as whataboutism, and to dunk on "the West". These groups of people are just pawns in their geopolitical rhetoric and strategy.