Update.
Minimal hassle at checkout. The front desk had a note to return my cert for ineligible night.
I explained the rate was a price match rate and I called Marriott to apply the EEO to that rate after it was matched.
She called manager who agreed with me immediately and told her to put it through.

What a cheap weekend.
Portland Waterfront Marriott pricematched to 69+tax, then used EEO and paid with 20% off GC.