There is a link at the bottom of the Radio Fórmula page to the audio interview. He spoke way too fast for me to understand him, but for those who do understand Spanish, the part about Zambada-Niebla and El Chapo begins around 5'30" in.)

As to Zambada-Niebla, he said the plea deal leaves "a bad taste." He said one of the conditions of the extradition treaty is that the receiving country return the prisoner when he has finished serving his sentence, so he can face any charges or punishment in the home country.

Why does he think the deal means Zambada-Niebla isn't returning to Mexico? Perhaps because the plea deal provides that if Zambada-Neibla's security situation warrants it, the Justice Department will request he be allowed to remain in the U.S. with his family after finishing his prison term. Or it could be because the plea deal says the decision whether request a sentence less than life is up to DOJ's assessment of the value of his cooperation. If he stops cooperating, or gives false information, he'd likely get a life sentence, which would make his return to Mexico while alive unlikely.

He was also asked whether the U.S. shared the details of Zambada-Niebla's cooperation with Mexico. He said he doesn't know. If it was shared, he said it would not be with his office, but with the Ministry of the Interior. His office only knows about shared information in cases they act on.

“No podría decirle qué nivel de inteligencia se comparte, excepto en los casos en que nosotros hemos actuado”.

It seems like the U.S. made no attempt to get Mexico's input on the year-old plea deal. For all the talk of increased cooperation between law enforcement in the two countries, it doesn't sound like there's a lot of trust built up.