If we ignore for a moment that he’s 30, it seems somewhat reasonable to ask her parents when she’s 18, whereas asking her parents when she’s 30 seems weird.
Now, a 30 year old man asking the parents of an 18 year old woman is weirder than a 30 year old man asking the parents of a 30 year old woman, but not because asking the parents in that situation is weird, but because he’s 30 and she’s 18.
Well it seemed like in your previous post you were contradicting yourself.