Another problem is the kidnapping of a passenger who then got promptly very sick and damaged in the friendly heavy hands of the KGB and police. You know, the usual thing the totalitarians do.
Fair enough if you want to criticize Russia for being a kleptocracy that assassinates enemies on foreign soil, but diversion of flights to capture enemies of the state and then not treating them well in captivity is unfortunately not a hallmark of totalitarian regimes but a general feature of western statecraft as well, so let's not blow this tit-for-tat response out of proportion.