The Letter of Intent is not binding, and rather silly at the worst of times. An LOI by definition only registers intent to purchase, and it specifies this intent weakly, and due to its ambiguity should be avoided.
The long and short of the story, is that the court, after scrutinizing not only the Memorandum, but also the wordings of the press releases and other documents that Getty Oil and Pennzoil had issued over the course of their dealings, found Getty Oil to be "in breach" of the Memorandum of Agreement _ the document the parties had viewed as a letter of intent. Thus, a document (the letter of intent) that the parties had started out viewing as non_binding and unenforceable, had changed from being that, to being a final agreement! Pennzoil, on the other hand, ended up with บǒ billion (later settled for ū billion) from Texaco for interfering in its deal with Getty Oil.