There seems to be this unspoken assumption that you can't do business if you're not nice.
This is definitely not true. If I were Jobs (which I'm arguably not, so it is possible that you can't 'get there' by being nice) I would have seen quite a few possibilities achieving the same without coming off as a jerk.
Maybe we disagree on that, but I don't think you need to be like that in order to succeed. Some of the wealthiest people that I have known would never think of treating another person that way, business or not, and I find it surprising that Jobs would do this. It's just my personal take on this, don't make it in to an absolute.
We agree on that you don't have to be jerk to be successful.
I disagree when you say they haven't been nice with Andy. They've been "hard", but not mean (to me) and certainly not jerks. Steve used a fallacy to move his agenda but that's typical haggling (What! This used car is mint! And you want me to sell it for that price? You want me to close my business?!!).
Let's not forget the story is told from Andy's point of view. Bill and Jobs were probably very assertive and Andy might be sensitive to the point he perceived that negatively.
Do you mean they should have been "nice" to him? If yes, why? They were doing business, not having a cocktail party.