Last time. It is an invitation to be privy to information that is not in the public domain and that the owner has no obligation to put in the public domain. That's it. There is no compulsion and nothing sinister about it. If the owner wanted to be totally secretive he simply wouldn't make the offer in the first place. Please just accept that you don't know about NDA's; there's no shame in it.
Nobody has ever been forced to sign an NDA. I respect your football knowledge and acknowledge that it is deeper than mine. But on this subject I'm afraid you are talking nonsense.