> Those with obesity and low WC [waist circumference] were not found to be associated with a significantly different risk of outcomes compared with those who had normal weight and low WC, except for all-cause mortality, for which risk was significantly lower.

If I'm reading that right, it sounds like obesity (and therefore BMI) is still a better predictor for all-cause mortality. Perhaps waist circumference is better at predicting cardiovascular risk but BMI is still useful.