Heh, sorry about the late reply, but his experience in the short lived Hungarian Soviet Republic involved their "quartering troops" in homes/apartments like his, something that at his age and the context he found profoundly disturbing (this is from memory of the recently read and superb The Making of the Atomic Bomb by Richard Rhodes).

On the other hand, this was made as a semi-joke by him, so I'm sure it has nothing to do with his memories of events back in 1919.