Not true, even on Cat 1, you can arm BOTH autopilots on approach
It is true. While you CAN arm both, Aluminium shuffler said that Cat 1 approaches are NORMALLY flown single channel, which is absolutely correct. Although, I don't agree regarding autothrottle being disconnected on the go-around - normally the go-around is executed by selecting TOGA, which disconnects a single channel A/P and sets reduced go-around thrust.