I'd say YES, the ad is misleading, UNLESS Xotic PC supplies the fully-featured version of Creative THX TruStudio PRO. Xotic does customize the standard ASUS models, so it would not be unexpected if they did supply the full version.
I'd give 'em a call. Maybe they forgot to install it on your system. I did see a case where they forgot to reconnect the WIFI card antennas on a customer's system, so they are not above making mistakes.
G74SX-A1 - stock hardware - BIOS 202 - 2nd Monitor VISIO VF551XVT