I definitely think that giving Gaston an animal sidekick in the season premiere (mind you, our first impression of the show after a 2 year long hiatus), and not following up on that, (or giving Gourmand any more individual appearances in the season) is... an odd choice.
Personally I think the idea of the villains having "pets" to use for their dastardly schemes is a very good idea. Because lots of people in the world who are animal abusers will often own pets themselves, which brings up a very large but very important complexity about the human mind.
It would be a waste for Nostril to be a one-off appearance.