Let’s look at what possible motive could Russia have for endorsing Bernie for president. 1, Because he’s a socialist. Answer: Very unlikely, because socialism is not communism–and is in fact more of a danger to communism than a democratic government would be. 2, Because Bernie would be likely to endorse Putin if he became president? Very, very unlikely since Bernie has never said anything to possibly lead Putin to believe that.
So, what could be the reason for the endorsement? In the wilderness of mirrors that enshrouds most intelligence ploys: what if they think Bernie will be a front runner and now is their best chance to tar him with the very same brush that has caused President Trump so much misery by their endorsement of him. Think about that as a reason that make sense in the peculiar logic of intelligence.
or even more nefariously: what if in his youth Bernie had endorsed communism thinking it was the wave of the future.