Rufus knew a lot more about dating than anyone might give him credit for, even though he'd never really had the pleasure (trouble?) of doing it; he certainly would not have needed help or advice from Cloud.

Cloud, however, might need advice from him after this. Or at the least assurance that his father was, indeed, an asshole. Which is probably why he hands the other blond the folder rather than speaking, letting him read everything he had found and out together to substantiate the rumors.