I just finished talking to grubhub cs and it seems they're still honoring codes that were applied:
(Grubhub CS) Sorry for making you wait! I've seen that the promo code has been successfully applied to that order and went through our system with no problems. Promo codes for the emote are still being sent through this week! They are having some issues because of the large quantities of requests but you should receive your code throughout the next few days!