My objection to your previous message is that you must be assuming he was locked away. If this was the case, why was he let go to Hungary?
Someone else recognized the language he was speaking, and that it wasn't actually gibberish (and so he wasn't some crazy old man).
It is really shocking that he never picked up Russian. I understand that Russian and Hungarian are almost as different as Japanese and Hungarian, but he should be able to learn the language just by hearing it.
Something even the USSR was pussyfooting around in its later stages…