Russia is a strange and dangerous bedfellow but given the nature of US “support” over the last 7 years I can see why Israel would consider a partnership. Perhaps the purpose is to hedge bets against another Democrat in the white house after Obama.
I think the Germans called this “Realpolitik.” There is a new boss in the Middle East, and it’s not us. When the boss changes, you cut a deal with the new boss. The Israelis would be foolish to not explore an arrangement with Russia, but as you said, they best be very careful about it.