Okay but logically kidney issues leading to high creatine does suggest that creatine is not all that good for the body, no? else why would the kidney keep it under control?
Maybe they aren't! But you can't infer that from the mere correlation. Hence that phrase about its relationship to causation.
In other words, it's not a very reliable signal for kidney disease. There is a more reliable blood test called a "Cystatin C" test.