I don't think they'll have any issues at all, providing their names are on the reservation (which you state they are). The only problem they may have, is that they won't receive any Platinum recognition without you turning up (and I imagine you'll want those for your room when you arrive).

If in doubt - make sure your companions are well versed on what you've booked... and as a safe-guard, maybe give the hotel front-desk a call, and just explain what is going on, and what you'd like to happen. I'm sure they'll be very accommodating.

No need to panic at all.