The throat singing relies on the voice maintaining the fundamental with another area producing the natural overtones of that fundamental tone. if you analyze the overtones, you find that they are not "tempered" as we know it but some of the tones are in the cracks, so to speak. The idea behind overtones created the basis for the system of harmony that we now know however this example is not a typically harmonized development which came later when musical instruments created tones that were slightly out of tune. Harmony that we hear today is slightly out of tune. Pythagoras was one of the few constructing tones that were mathematically accurate but would sound out of tune to us today. Bach's "Well-Tempered Clavichord" was as are all keyboard instruments slightly out of tune with the overtone series. Some stringed players compensate by playing sharped notes slightly higher and flatted notes lower but the overall harmonic effect has
to be slightly out of tune to get the fullness we associate with chordal instrumental or vocal harmony. The reason it doesn't sound out of tune is that we have been conditioned to hear harmony a certain way which resonates with our cultural appreciation of it.