Why doesn't Mexico make its secondary language Nahuatl?

I'm doing a paper for my class about Mexico and its indigenous roots, not sure if this is the right subreddit for this but I might as well try to ask anyways just to get feedback from the Mexican people themselves on their thoughts and opinions. Feel free to comment in Spanish, I can understand it better than I can type it myself. 1st off, I know Nahuatl isn't the only indigenous language of Mexico but it was the language of the Mexica or "Aztecs" who were the majority and basically the ruling people of the empire before being overthrown by the the "Spanish army" which was pretty much 99% indigenous allies that hated the Mexica. My question is, why not preserve the language or make it a secondary official language the same way you preserved a lot of other parts of your indigenous culture? its still alive but a small minority of people still actively speak it. I know theres mixed feelings surroundings the indigenous heritage even with those who are nearly fully having some reservations of being labeled as native. Any real feedback or thoughts from all sides would be helpful, gracias!