Its meant more of a turn of phrase than literally. I'm sure he didn't actually run to Russia, but in transit or not, he chose to run from the US authorities and accept political asylum in Russia. I'm sure most would do the same seeing what happened to Assange. Also, I've just read some of his recent tweets and he has somewhat suggested some opposition to the war in a more-obvious-than-id-expect kind of way. Seems like he's in a bad and growingly frustrating position.