Sigh.

Correlation != causation

It could be that people that spend more time in the sun are busy getting exercise. Which lowers blood pressure.

It could be that people that spend a lot of time in the sun know that they have skin damage, and are more likely to detect melanomas due to more frequent checks of their damaged skin.

Summary: More sun exposure may or may not lead to lower risk of death on two fronts. It seems far more likely that getting exercise and frequent melanoma checks lead to better outcomes, and both of those are correlated with being in the sun, but by no means necessary to the outcome.