Granted, there are people who deactivate JS for whatever reason.
The intersection of "people who deactivate JS" and "The addressable market of Four Seasons Hotels" is likely small enough that the lost potential sales wouldn't even cover the cost of development.
I just moved here, so I'm getting to know the neighbours. One of them had a wi-fi problem. It turns out his TP-Link admin interface relies on JavaScript to function. He uses the No-Script Firefox extension. He's a retired chairman of a PVC company, who moved to the Canary Islands for his sabbatical. Judging by the house, he's part of the addressable market.
I think it makes sense that high-value employees with access to sensitive information get basic cybersecurity education. Therefore, some of them block JavaScript.
Catching deactivated JS is not really big, in terms of development costs. But especially companies like "Four Seasons" are usually the ones that live by "Every missed customer is one too many".
And i dont think that money was an issue in this project.
Except that the cost is near zero if you approach it right. It also means supporting many mobile browsers that usually break js and providing a better experience on slower connections (3g, edge, whatever).
There's a specific touch optimized site that works for mobile. It doesn't look like it or the iPad optimized site are done yet either since they redirect to preview.fourseasons.com, but they're definitely aware of mobile devices.
The intersection of "people who deactivate JS" and "The addressable market of Four Seasons Hotels" is likely small enough that the lost potential sales wouldn't even cover the cost of development.