Nah it's relatively straightforward. Russia has had a tumultuous experience with Islamic extremism and is trying to acquire a sphere of influence in the middle east now that the US is now leaving a vacuum. Allying with Assad and Israel in tandem fulfils both objectives seamlessly.
Russia started that process long before the US began to withdraw. The nuance you may be missing is that Russia seeks to turn the Shia into their primary ally, since the US "picked" the Sunni, which was a total flip from historical relations.
The Sunni in Palestine are therefore useless, and Israel is pragmatically the better choice, so long as Russia believes Israel is neutral and not part of the US' sphere of influence- which, by rights they should be, but they really aren't. Turks tend to identify as Turkish before Sunni Muslim due to years of Turkish Nationalist (Kemalist) rule, so Russia can try to seduce Turkey, ally with Iran/Syria, and woo Israel, allowing them to form a powerful Asian bloc and escape US sanctions through circuitous trade.
Iran, Russia's big Shia ally candidate, is meanwhile reluctant to rely on Russia alone, because it would effectively turn into a puppet state. It's trying to use Palestine to subvert Israel, taking the pressure off from Russia, which is why it and Syria keep arming Palestine while running operations to try to convert them to Shia (and letting the Sunnis blow themselves up with shitty Iranian rockets). Before 2000, <1% of Palestine was Shia, now that number's often quoted at about 15%.