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.
"Buyer who is serious, ready and able to purchase [crude oil], will sign [an] LOI and all the necessary documents that protect the rights of the Brokers and proceed. There is nothing to lose in signing those documents. This is how it is usually done and this is how it should be."