No, friendship has respectful boundaries. It isn't a free pass to involve yourself in every aspect of one's life. Marriage doesn't even give you that. Learn the limits.
This is not some minutiae. This is a real relationship at stake, I would feel morally obliged to demonstrate to my friend that he was making an error. That's essentially what friendship is about. The Stanford Encyclopedia of Philosophy defines friendship as " distinctively personal relationship that is grounded in a concern on the part of each friend for the welfare of the other, for the other's sake." To not have that concern, to not be worried by such things is a problem, but to be aware of it and to not take action upon it, as you deem it to not be your business, would be tantamount to declaring "I am not a friend of yours".
Simfan...I really don't know what to say.
Would you prefer if I just pulled things out of my rear end?
That depends. What's in your rear end?
