Richard Ellis (Hi, if you are reading this!) makes a very good point in his book The Search For The Giant Squid about Cousteau's description.
Cousteau records that from his mini-sub porthole at 800 feet he saw a very large cephalopod and that it was an unearthly sight, astonishing and terrifying. It fixed its huge eyes on him, then suddenly it was gone. The impression it made was one of size and power, he stated that he could understand how formidable a giant squid must be. (Forgive the paraphrasing, the passage is too lengthy to copy out in its entirety).
Cousteau fails to give a location or date for the incident and at no point does he state that that he saw Architeuthis. The squid may be huge, but what does that mean? The term is relative; my pet cat may be huge, but that does not make it a tiger. The implication for the reader is that he saw a giant squid, but if had really seen one I'm sure he would have been more than forthcoming with the details, afterall, Jacques Cousteau was not exactly media-shy.