Considering Israel is surrounded on all sides by nations that would love nothing more than to exterminate them, I think they have every reason to worry about their national security.
As for the Israeli vs Russia / Georgia argument, places say that Georgia didn't have any armored divisions and that their tanks were nearly all T-72s. Whereas Israel does have armored divisions and also fields the Merkava III/IVs. On the other hand, until a few years ago, Russia's military was dying from lack of funding, and while their technology is top class, they lacked actual numbers to be effective.
Israel would put up a hell of a fight for sure against Russia. Israeli forces are not only trained and up to date technologically, but they're also battle-tested and determined. They're also supported by the USA, who can field more tonnage out on the water than the next fourteen largest navies combined, and enough tanks and planes to surpass both "quantity is its own quality" and "quality over quantity". They have quality and quantity.
Basically, if Syria and terrorist groups get their hands on modern SAM systems, it means they can knock down Israeli jets, which means they can make Israel more vulnerable, which means they have greater incentive to attack and exterminate the "heathen" Jews. So to Israel, the weapons systems are a clear and present threat to their security and safety.