[Svartalfiar]

If you keep reading:

The seventh note, SI, was formed using the initials of Saint John, “Sancte Ioannes” in Latin. But it was added a bit later on, in order to complete the diatonic scale.

[map]

The first six tones appear with their respective syllables initiating the first six phrases.

The 7th tone does not appear as a phrase-initiating syllable. Sancte Ioannes does not even touch tone 7.

The headline is artificially stretching it.

Take it from Guido: hexachords rule.