Loewen suggests that when textbooks celebrate Columbus instead of creating a teachable moment. How?

From the text:

The way American history textbooks treat Columbus reinforces the tendency not to think about the process of domination. The traditional picture of Columbus landing on the American shore shows him dominating immediately, and this is based on fact: Columbus claimed everything he saw right off the boat. When textbooks celebrate this process, they imply that taking the land and dominating the natives were inevitable, if not natural. This is unfortunate, because Columbus’s voyages constitute a splendid teachable moment. As official missions of a nation-state, they exemplify the new Europe.