Even if the guards are basically mall cops (and they're probably at least armed, if not moonlighting or retired actual police officers) , he can either; a) Gun them down, and the next person to show up at the gate after he's gone reports it to the police, b) Show them how outgunned they are, in which case IF they let him in they can call for reinforcements (including the DEA agents tailing Nancy who'd LOVE to hang U-Turn's head on their wall), or c) Try to buy them off. 40% chance at best and that drops exponentially with each guard more than one who's at the gate at that moment.