"Even Mexico's elections were very recently manipulated by USAID" - according to one politician.

The article only named 2 groups that received USAID funding:

Mexicans against Corruption and Impunity

Article 19 (a free speech group)

Now I don't know if these groups do what their names advertise. But Mexico is a sovereign state. If its government thinks it's against the national interest for Mexican non-profits to receive foreign money, they are free to pass laws to do so. And far more likely to work than telling a foreign government to "please stop sending money".