You can debate this further...the $100 Platinum Gift Guarantee is compensation for bad service just as the credit for the room was for bad service. Both are monetary in nature to compensate the individual. Would you keep the $100 or would you give it to your company?

If you buy gift cards at a 10% discount, do you pass on the savings to your company?

Using a free night certificate or monetary voucher such as bonus bucks, do you still expense the full rate for the room to your company?

Your credit card gives you 5% back for hotels, do you discount your hotel bill 5% before expensing it?

The lines are blurry between what is personal compensation and what is legitimate savings to be passed on to a company. I could argue that the company is due all these cost savings, but I suspect the company does not expect these savings to be passed on to them and would allow the individual to reap these benefits.