Wikipedia GAN history (and talk) indicates it's not quite as clear cut as your framing, and this answer below on that subject from somebody who blogged the idea several years previously demonstrates there is often a hinterland of discussion that gives rise to the (genuinely) independent ideas of Goodfellow et al.
In this case the central idea doesn't seem to have been completely original to Goodfellow, though the credit is his for fully pursuing it to implementation in the current model.
https://stats.stackexchange.com/a/301280
Note: the linked answer - while in the context of the well known Schmidhuber can of worms, is actually the more obscure and very polite challenge from Niemitalo (who is mentioned in the Wikipedia history). The point stands though, regardless of actor.