Plenty of grandparents have had a perfectly good relationship start that way, but
This should not be an argument someone makes in the modern day? What's the purpose of communicating this. You can't use the argument for present day people, and you shouldn't make people think you would.
Oh, don't worry, I fully agree. Pedophilia, grooming, and etc are inherently bad, full stop.
But when it comes to this specific circumstance, as I stated, it really rides that legal and moral gray line where I really can't give a proper answer. Hence the "Well, it really depends."