More on Ruben from TH Rigby, Australian historian considered the world's foremost Sovietologist:
The Vitaly Petrovich Ruben whom Mr Wilsey met in 1984 ['82, actually] was indeed at that time Chairman of the Chamber of Nationalities of the USSR Supreme Soviet. Born in 1914, evidently in Rybinsk, a town in the Yaroslavl region of Russia where he graduated in agronomy from a technical high school and worked briefly as an agronomist, during which time he must have joined the Communist Party as he was put in a Party job after graduating.
By 1947 Ruben had been sent by the Party to Soviet dominated Latvia, working his way up through various Party and government jobs, till he became Chairman of the Council of Ministers of Latvia from 1962 to 1970. His next job, an essentially ceremonial one, was as Chairman of the Council of Nationalities of the USSR, and that's what he was doing in 1984 ['82] when the young Sean Wilsey met him. I have no record of him after 1984, but since he was then seventy he presumably moved to a respected retirement. I presume he was of ethnic Latvian extraction, the Latvian form of the name being Rubenis, but I cannot confirm this.
Please give my greetings to Stephen Kotkin, whose work I greatly admire.