Let me just say that this episode was needed for the sole purpose of showing off what else Pokémon Connoisseur's can do. Therefore it's not filler.
To be more precise- It's not a filler in between two canon events; Finding out Opelucid Gym is closed in the start, going to Virbank City in the end.
I mean we were going to find more about them eventually. That's for anyone who thought this episode wasn't needed as Cilan got no development.
Just because some character is not high on the popularity list it does not mean everybody doesn't like them.
To anyone who does it: stop stating this like it's a fact. I know lots of people who like unpopular characters.