You do know that honest science rarely makes definitive statements, right? It may be a spurious correlation, but the next most likely explanation is that all the men lied about their results in a way that perfectly mimicked the expected results, and they did so without any coordination, and over the course of years. Or it's just a massive coincidence that is only true of those men.

https://www.health.harvard.edu/mens-health/ejaculation_frequency_and_prostate_cancer