If the cops raid the place, handcuff all the patrons, interview them one by one and lean on them, specifically ask them "how did you get into this place", what odds do you want to take a bet on that at least several give the names of who got them in? (some of them perhaps guys who you got in?).
Realistically, the cops have no interest in busting the players and if they tried, I don't know how much water this particular argument would hold. I don't imagine that any DA would want to try to convince a jury that a guy was guilty of inviting his friend to a poker game.