The only reference in that wiktionary article is a Polish dictionary. The Wikipedia one has no references. I'm French, and I can tell you with confidence that someone saying "bon viveur" would be met with laughter and contempt.
The GP is bashing Europe for "recycling its long tradition of aristocratic affluence" but is at the same time using fancy foreign phrases -- "bon viveur", "nouveau riche"... What is be the reason? Well, to show off and lend credibility to the bashing: "see, I'm part of the circle too, I know the shibboleths; my criticism has more weight because it comes from an insider", is the subliminal message. Using the phrase wrong just looks foolish in these circumstances. Like a child who learned a complicated word and tries to impress with it, but uses it wrong.