If I am correct then people with low bf/ % but with as lot of muscle might be at risk as well as people who are obese due to excessive b/f.
Carrying excess fat has more risks than just the added strain on the heart. Excess fat contributes to hormonal and metabolic issues that can be detrimental (diabetes is just one off the top of my head).
But I think that the supermassive, even though muscular and low fat %, bodybuilders are at risk for health problems. I don't think the human body was designed to carry so much excess weight, be it muscle or fat. Both excesses cause problems, imo.