Or these men simply lead more active lives with regular exercise. Hard to tell.
Of course, they cannot take everything into account.
Short of having a thousand identical twins locked up in a room from birth you're swimming against a very strong tide. Long gone are the days when science was as simple as castrating a rooster and grafting his balls back: https://en.wikipedia.org/wiki/Arnold_Adolph_Berthold
They acknowledge that they are just looking at the number of prescriptions and that the research doesn't show that the drugs themselves were reducing people's risk.
It could equally be the amount of sex that is reducing the risk.