That's pretty calculating though. Essentially you're saying 'be nice' because there is money in it. But actually people should just be nice even (or maybe especially) if there is no money in it.
Naturally character is better highlighted by what you do that has no tangible reward, and done in the dark, where you think no one will see it. And being nice, and compassionate, and charitable are things that should be done because it is the right thing to do, regardless of reward.
The quote is in the same vein as the original article; the general thrust of the article is that being nice pays dividends, which could be interpreted as being calculating as well, I suppose.
But I don't think that is the intent. I think the intent is the same as my comment - to just highlight the benefits and renewable nature inherent in being nice, not saying that is the reason to be nice.
It sweetens the deal without actually costing anybody anything. Even if nobody takes home any additional dollar bills when the business is concluded, if everyone is trying to be nice, it may be worth going ahead with it anyway, just to build mutual trust and confidence for some future transaction. Though you can't ever spent it directly, and it is difficult to measure, reputation does have monetary value.
Essentially, it's like having a magical purse of silver coins that is never empty, but you can't ever spend even one of them yourself. You can only give them away to other people. Is it better to hoard those coins to yourself, or to give one to everyone you meet?
It could also be simple.
If you charge someone so much that they can't sustain their business then you might win but at what price.
v.s If you charge someone what they can afford then they will stay in business longer and then you might end up winning in the long run.
And that's just one possible interpretation :)
But you're right, there are more interpretations possible and not all of those are negative.