That article is nonsense.
I'm not sure where the idea that Arnold liked deca came from. Never heard that.
I know from some reliable sources what Arnold SUPPOSEDLY took. I've posted this dozens of times. He was known to use a vial of primo and 50 mgs of dbol a day. Whether or not that's 100% accurate, no one will ever know. But that's the story from those who knew him.
The assumption that he stayed on dbol year round is nothing but that bloggers out of his ass imagination. Arnold lost A LOT of size in the off-season. Yet, he responded amazingly well to dbol. So saying he stayed on not only makes no sense, there'd be no reason for him to do it.