Alexander doesn't screw around
But I agree. The role of the melody in music, and whether you need it or not, is a complex discussion. In a sense, melody is everything - but Slayer didn't need melody.
However, the only thing that the example in this video proves is that you can full well write music without melody and have it sound like your average fare epic media fart. Not sure that was in dispute in the first place. The message seems to be: no, you don't have to think about melodies or anything. Just write some bullshit like this, somebody's gonna eat it up anyway! Not sure that was intended. So yeah, it's kind of counterproductive and seems to encourage people to just don't give a damn and confidently produce bad music - melodic or not.