I have only limited formal music education, but I am an ardent amateur performer and listener. But I agree with the person who ran down the aisle at the 1970 performance, yelling "Stop! I will confess!"
Western music requires rhythm, melody, harmony. (though rhythm may stand nearly on its own.) Beauty can be subjective to a degree (some non-Western cultures do not find dissonant notes to be objectionable in an otherwise harmonious piece) but coherence of chord progression and melody are fundamental.
This "Four Organs" piece is to my ear a timing algorithm, far less interesting than a perpetual canon ("song in rounds") because it implements only rhythm - melody and harmony are missing. Frère Jacques... no, scratch that, even "Happy Birthday To You" seems a grand compositional achievement by comparison. It is a meager elevation beyond the sort of finger and timing exercises every music student performs -- play a scale in eight notes. Now dotted eights, now triplets, etc. This sort of timing-coherence pattern is pretty common in percussion -- two musicians playing in different time signatures so that the beats periodically align. But the arrogance of four organs playing a monotonous note stretches this simplistic exercise beyond any value, and to raise it up as a great achievement is absurdity equal to the art world's all-black canvas, empty box, or filled rubbish bin.
I'm going to use Rush Limbaugh's definition of art : (paraphrase) "Art is what I can't do. I can throw paint on a canvas. I can glue litter to a floor. I can pound the keys of a piano. That's not art.
I cannot carve a statue of David from marble. I cannot paint the Mona Lisa or the ceiling of the Sistine Chapel nor compose an orchestral work. These are all art." [edit: added last sentence]