Even taken at their word, it doesn't change the fact that they are using documentary procedures that are unusual, and abnormal. Contact any business college, or speak to established traders or people working for large multinational corporations. Talk directly to international bankers on this.
Moral of the story? If you're ever contemplating using a Letter of Intent in a business transaction, you had better watched out, it may not be as simple a matter as you might think. You better be very cautious, for it could result in unforeseen and unpredictable consequences!