I finally realized who Fennec reminds me of. Inami Mahiru's friend in Working!!, the one she talks with in Episode 7 of Season 2, who deliberately withholds her advice from Inami and tells herself (unconvincingly) that she's doing it out of concern for Inami, and not because it would be funny.

That kind of goes along with Ueyama-sensei's portrayal of Fennec here, but I get a slightly different vibe from Fennec than that. To me, it seems like she knows Raccoon's ideas and decisions are frequently rash and frequently in error, but she knows that she can't always get through to Raccoon when the latter is stuck on an idea. Instead, as a good friend, she goes along to be sure sense is interjected, at a moment that it might actually be received.