Exactly right. Their message is simply anti-gringo, pro-Aztlan.
Their goal isn't so much to colonize the southwestern US so that it can one day be re-annexed by Mexico, as making certain that mestizos and their barrio culture will one day make up the majority of the US population and call all of the political shots. In other words, they want a US economy, welfare state, and infrastructure combined with Mexican underclass culture and politics. They're too stupid to see that these are mutually incompatible.