They're probably all associated with his Chase card (or another card perhaps?). I'm not sure if/when LoungeClub verifies the CC, and whether they just check to see if it's active or if they also check to see whether the crd is eligible for free LoungeClub.
I did use my Chase Ink when I signed up....bust used the same Ink card for four family members (not including myself)...none of whose names appear on an Ink Card.
Someone will have to try and use the link provided, without a Chase Ink Card, and report back. It may work -- as once you've passed the point where you enter the verification code, it appears that you cold enter any CC number (presumably, though, they check to see if the card is valid, because that's how they charge you $27 per visit beyond the first two visits that are included).
I could be wrong, but my gut tells me it may just work. By the way, not that this supports one way or the other per se, but you're also not supposed to be able to get four Lounge Club cards on the same Ink Bold card.