That's because it's not a "Pachanga" in the early 1960s dance fad pachanga sense. This audio you posted is a remake of the Eduardo Davidson original. Which (the original) was a Merengue. Just a Merengue rhythm played by Cubans. I've read where they've it's been redefined as a Conga-Merengue or some other name to give it a homegrown authenticity. But Davidson's "La Pachanga" is a Merengue (a la Eduardo Davidson's rhythm section). The song title for Davidson's composition is an allusion to a "party," and not a dance craze (like "the Twist") or a codified music subgenre of Son.
Pachanga post-Eduardo Davidson has a rhymthical approach (like ALL 'Son' based music since day one). What John Santos refers to as "A Caballo" is a reference to a certain kind of groove rooted in the Charanga tradition that lends itself to hopping and skipping in place. Orquesta Aragon were the "faces" of this in Cuba. The dancers would whip out a handkerchief and 'snap' it or wave it towards their dance partner. That phenomena got transplanted to NY, and not necessarily or exclusively by Cubans (Puerto Ricans had been making their way to Cuba since before anyone) and was applied to the rhythmical approach that would eventually become synonymous as a NY-style pachanga.
Benny Velarde pointing to 1961 as a starting point is in reference to the "popular narrative" that Johnny Pacheco is who became the face of the Pachanga becoming a dance craze (which he was) and when it first made national news. But the dancing part, and the music style that got crystallized into becoming, goes back further, and not directly to Eduardo Davidson. But to Jose Fajardo. Who first came to the U.S. in 1957. That appearance at a hotel (he "sat in" upon visiting the Palladium ballroom after his hotel gig, but was not booked to perform) is what impacted Charlie Palmieri, Mongo Santamaria, Johnny Pacheco, Lou Perez, Belisario Lopez, Bolo Martinez, Joe Quijano, Ray Barretto, Armando Sanchez and others to pursue a an uptempo Charanga dance format "...a Caballo."
Fajardo's music, albeit not as progressive, is the link to the NY "Pachanga" emerging in the early 1960s. As well as the all-brass conjuntos and vibraphone-oriented ensembles in NYC (like Eddie Palmieri's "La Perfecta" and the Joe Cuba Sextet) emerging to go from sounding akin to a big band or full orchestra sound or approach, to a more Charangeao' (or Charanga-ish)