This one may be a stylistic choice. "Borrowing" the words of other languages is a time-honored past time among ... pretty much everyone whose every spoken any language, ever.
The trouble is that English and French don't really mingle all that well because our pronunciations are radically different, so even though we might want to borrow the French word for "a hint of," or "a trace of," leaving out the cedilla (squiggly thing on the c) would read like, soup con. Which, although it sounds tasty, probably isn't a nefarious plot to steal soup.
(BUT IF IT WAS, I BET MISTBEARD WAS INVOLVED!)
Leaving in the c-cedilla is a way to say to English speakers, "Hey, we borrowed this word and holy hachimaki do we sound suave saying it." This, of course, implies that soupçon was purposely used; which it looks like it was... but I'm willing to bet ten Gil that a LOC will have something hilariously snarky to say about it... so...
/spotlight <LocalizationTeam>