I am quite sure you only get Gold Status:

www.priorityclub.com/ambassador

Valid at over 140 InterContinental® Hotels & Resorts worldwide, Ambassador status also automatically elevates you to the Gold Elite level of Priority Club® Rewards. So every time you stay with us at InterContinental Hotels & Resorts you’ll receive exclusive privileges (recognition) (relaxation) (rewards) and you’ll earn valuable points or airline miles. In addition, your corresponding Priority Club Rewards membership entitles you to Gold Elite member benefits when you stay within the Priority Club® Rewards family of brands - Crowne Plaza®, Hotel Indigo®, Holiday Inn®, Holiday Inn Express®, Express by Holiday Inn®, Staybridge Suites® and Candlewood Suites®. All for an initial fee of $150USD.

The platinum status was only granted with the old Ambasssador version which was in the Six Continents Club. There would not be any incentive for PC members who don't stay at ICs to earn Plat if they could buy it for $150.