I understand that legally they "can" give you the JW and call it a day - they can probably just put you up at the Sheraton near the airport as well as long as they give you a bed to sleep in, a roof over your head, and access to dining which seems to be their understanding of meeting their obligations to their guests, legally or otherwise.

I meant that from a PR/sensibility/moral standpoint they "can't" do this because they are not meeting the expectations of the guests at all who specifically booked at the W and they may suffer from the backlash of doing that as you have pointed out.

I think they can split the guests between the Ritz and the St Regis and if they're paying cash to these resorts anyway then there are comparable non Marriott resorts they can transfer guests to as well. The JW should only be an option if it comes along with an offer of compensation (perhaps meals included?) that the guest can then decide if it's worth for them to accept that or not. But it shouldn't just be the JW or bust.