Agree the issue here is not that IC is incorrectly categorised as not being luxury, but that the likes of JWM are categorised as luxury.

In terms of the major chains I think only Park Hyatt and certain RCs and St. Regis are luxury, the tiers are something like this in my head:

Luxury - PH, RC (possibly), St. Regis (possibly), Luxury Collection (possibly)

Premium (but not luxury) - Conrad, GH, IC, JWM, W, Fairmont

Upper Upscale (whatever that means) - Westin, Hyatt Regency, Andaz (with notable exception of e.g. Tokyo which goes in tier above)

Upscale - Hilton, CP, Sheraton, Marriott, Hyatt, etc.