> I'm assuming they'd like to avoid spying on citizens of states they depend on militarily/politically or that have the capability of retaliating.
It's an open secret that Israel has been conducting economic and military espionage against the US[0][1][2] and stealing civilian and military technology for decades. This "blocking +1 numbers" is rather a thin veneer to prevent third parties from endangering the "official" Israeli espionage program.