Perhaps David you should try to actually listen to their streams before saying something that is incorrect. All of their stations branded "Milenio" have switched to this format. Chihuahua, Monterey, Saltillo, Guadalajara, Torreón, Tijuana. And they are all over the air FM stations not just streams, but listen for yourself.
"Milenio" is a corporate name to identify an existing news product which, on radio, is mostly a talk format (They call it "news" in the corporate section of the web page).
The Milenio brand is principally Mexico's USA Today newspaper, a print and online daily, with local editions in a dozen cities. It has TV in three cities, also called Milenio, and also news talk. It is on cable services all over Mexico. The radio talk format is a brand extension.
There is no "milenio" music brand.
Keep in mind that just in Monterrey, they own 14 stations, only one of which is an AM / FM news talk simulcast, tied to the paper and TV channel.
The format on in Tijuana... soft AC hits from Bobby Vinton et. all... is likely a filler while they transition to or build out the Milenio format in that market, which is talk. It's also apparently a filler in a couple of other markets where they intend to expand the local talk on the Milenio stations. Unlike USA Today, the Milenio papers have true local editions with national branding.
As I said, this is a selection of "oldies" that were hits in Mexico, and tailored to Mexican taste in English language music. But it's fill, not a format.
Milenio is also the corporate brand for the news inserts on all the stations in the group.