Sounds like poor planning to me...

But I dont think the article states what type of air defense system shot the aircraft down. It's possible that it was brought down with a kinetic type of AA gun.

It's also very possible that the Russian aircrafts countermeasures did not work. Remember, the anti aircraft weapons only have to work properly once to bring an aircraft down. The aircrafts countermeasures have to work every single time.

What I find alarming and stands out more than the fact that it was "Isreal's fault", is the fact that a Russian aircraft was brought down by a Syrian AA/A fire. Every military aircraft that flies, has a friend/foe systems that "talks" to other allied systems and tells them that they are in fact a friend or foe. Why didnt the Russian FF system work? Yes, it was shot down by the Syrians, but the system was sold to Syria by the Russians. I've also flown with other allies aircraft and never ran into an issue of us identifying allied aircraft as an enemy.

What's interesting about this, is the US has been playing proxy war against Russia in Syria. Nothing nefarious about it, they do it to us and we do it to them. Obviously the Isrealis found out a way to screen their aircraft using Russian aircraft as cover.

The line of "reasoning" and the blame Israel mantra works well for a certain circle of people.