From the TMBG wiki:

The original "Why Does the Sun Shine?" was recorded in the 1950s and based on encyclopedic facts from the time, which were later discovered to be incorrect; rather than being made of gas, the sun exists mostly in the fourth state of matter—plasma. By the time the album's fact-checker, Eric Siegel, pointed this out to the band, they had already recorded the song and the accompanying video was already in the works. Not wanting to drop the fan-favorite song from the album but also not wanting to perpetuate incorrect information, the band was faced with a conundrum. While discussing the problem in the studio one day, one of the recording engineers, Jon Altschuler, suggested the band write an "answer song" called "The Sun Is A Miasma Of Incandescent Plasma," which is exactly what they did.

But the way you explain it, it's actually great how the Sun songs turned out. Because the first one was wrong on a technicality, now we get to see a scientific statement being revised.