From Fig. 2, it looks like the "hazard ratio" is minimized at a total cholesterol level of around 230 mg/dL, with both higher and lower total cholesterol levels associated with higher mortality. However, medical advice (see e.g. Cleveland Clinic page below) routinely asserts 200 mg/dL as the maximum for the normal range, with 230 mg/dL being "borderline high" and approaching the "high" band.

https://my.clevelandclinic.org/health/articles/11920-cholest...

In the discussion section of the paper, the authors write:

"The current cholesterol guidelines are heavily based on heart disease risk and recommend a TC range of <200 mg/dL as desirable. TC range <200 mg/dL, however, may not be necessarily a sign of good health when other diseases are considered. The diseases associated with lower TC levels and potential mechanisms have not been conclusively identified."

Time to eat more cheeseburgers?