What's the difference between a negotiated settlement and a shakedown?

Reihan Salam says it was a shakedown (but I'm not so sure):

The most despised multinational working in the United States agreed to pay $20 billion over four years into a fund defined to benefit Gulf residents impacted by the spill. Some have characterized this as a shrewd decision on the part of BP CEO Tony Hayward to contain the damage to BP’s reputation. Yet BP has received no assurances on future legal liability and it remains, quite appropriately, on the hook for environmental damages. The Justice Department has already threatened to prosecute BP, and a refusal to play ball on BP’s part would almost certainly have led to an even more aggressive campaign of public vilification, at the very least.

To maintain an orderly society, we should at least try to contain and manage our desire for vengeance. On closer inspection, this doesn’t look like much of a negotiation. Rather, it looks like what one would colloquially refer to as a “shakedown,” in which a stronger party, ignoring the conventions of a good-faith negotiation, all but forces a weaker party to bend to its will. But now that Rep. Joe Barton has, in fact, called the White House agreement a shakedown, he has, despite backtracking and apologizing, taken the political heat off of the president. Somewhere, Rahm Emanuel is smiling.

Where, exactly, was the bad faith?  BP is extremely well-represented by legal counsel and could have kept negotiating and, if it wanted, it could have stood on its legal rights and let everything be resolved in the courts. It took this deal — and do we know the real dimensions of the deal? — because that seemed to be in its best interest.

But I don't think there's anything really wrong with using the word "shakedown." It's strong rhetoric, and basically metaphorical.

shakedown

1730, "impromptu bed made upon loose straw," from shake + down. Fig. verbal sense of "blackmail, extort" is attested from 1872, noun meaning "a thorough search" is from 1914; both probably from the notion of measuring corn. The verbal phrase to shake down "cause to totter and fall" is recorded from c.1400.

We encounter this colorful, figurative language all the time in political discourse. For example, Obama's BP speech last Tuesday was full of military language. He called the disaster a "siege" and talked about a "battle plan." Big ... deal. And by the way, "a big fucking deal" — as Biden would say — is not literally fucking. It's the way we talk. And most of the time, like just then, it seems silly even to point it out. So I'm unmoved by the back-and-forth over the word "shakedown." It's more politics. I'm coolly unmoved... though I do think it was lame of Barton to use it and then not defend it.

What matters is whether Obama did a good job of pursuing American interests and whether, in the process of of pursuing American interests, he abused his power. Since BP could have rejected Obama's proposal and fought through the legal process, I don't see what's supposed to be the abuse of power. Salam doesn't say he thinks Obama will manipulate the federal and state courts, so what is the problem? More worrisome is the possibility that Obama's deal was too good for BP. It took the deal, and we should wonder why. Is this one of those things — like the health care reform — where we will find out what it is when it goes into operation?