Whether likely or unlikely, someone who purchased a trip relying on their Marriott status and the value it would provide for their hotel stay as a primary factor would have a clear case. In my batch of reservations, one such trip (to NYC) was made because the appeal of Platinum status made the weekend stay appealing enough for me to buy the airfare for me and my wife. The hotel room was purchased on a 21-day advance rate, so I'd also need to have my prepayment refunded to be made whole. I also made several other reservations on other dates that I can cancel without penalty (trips I was already taking, but would have used Starwood instead), and will do so if status is not returned. I am *not* making an argument on moral grounds, nor saying I am going to fight with Marriott about it; I'm merely pointing out that some may have a legal basis for a claim.

Delta made a similar error (in their case, release of a promo link - not false status) last year, and I raised a similar concern. They made good on the error by honoring the promo for anyone who signed up before they caught it. To protect themselves, Marriott would be wise to either revert back the errant statuses, or at least agree to change back any downgraded status, upon request.