Why does Russia care about the Palestinian Authority? They have no resources.
The palies were Russian proxies going back to Arafat. Say what you will about Putin, he sticks with his allies until the last dog dies.
Maybe Russia has animus against Israel. Take note of Russia’s thriving bilateral relations with Iran, in the same vein. Russia is not what one would call “capitalist”.
Russia would like to help the PA get all of the resources in return for a warm water port (Israel) with potential land routes to Russia—a place that’s not next to EU nations (see map, possible routes).