Thank you for sharing that link. In the article, Dr Kenfield recommends eating a maximum of 2 eggs/week (if you're including the yolk) and avoiding high-fat dairy, but also says that "Low-fat and non-fat dairy are not consistently associated with bad prostate cancer outcomes."

That said, there's nothing wrong with choosing to consume non-dairy products like oat milk, so if you prefer it, go for it! For a lot of people, it might even improve their digestive health, because many people have trouble with lactose.