That sounds like a poor experience, and I am sorry for your friends' trouble. Clearly, LX could have been more helpful.
But let me get one thing straight: Your friends to not speak English (nor, presumably, German or French?) and do not have paperwork to enter Schengen space. And yet they decide to go from California to Russia by flying LAX-LHR-ZRH-DME ? That is just asking for trouble. At any stage of this journey, things can go wrong due to IRROPS.
Why didn't they go straight to Russia, e.g. LAX-JFK-SVO?