They don't think of him. As far as I can tell, he is virtually unknown, except for very few people among those who are interested in Philosophy.
I think, Ayn Rand is more known (or rather less unknown) in France than Guyau.
You are right about the second one. It's a little summary chapter by chapter, available for free here. The author is a reader of my blog about Objectivism, and since he made that book, I've translated some chapters of The Romantic Manifesto.
The first one is supposed to be a biography of Ayn Rand. It was the only book in french about Ayn Rand since recently. The book was written by Alain Laurent, the publisher of Atlas Shrugged in France, who was also last year in a lecture with Yaron Brook. I was in the public, so was the author of the second book The Esthetic Philosophy of Ayn Rand. And I asked a question. Alain Laurent is also the publisher of The Virtue of Selfishness, but he removed most of the chapters, as I say in my video, including the introduction, to publish his own introduction.
Because he is the publisher of Ayn Rand and because of that book, Alain Laurent is viewed as the "expert" of Ayn Rand in France, so when the french medias talks about her, they have Alain Laurent as a guest. In my opinion, it's a scam, because Alain Laurent doesn't understand Objectivism at all (It's easy to prove, he disintegrates all ideas), commit some errors and is regulary very critical about Objectivism grounded on his non-understanding and errors.
One single example (among plenty): In the book you mentionned, he advocates that Ayn Rand is not a philosopher and that she had never read Kant, and criticize her for never quoting other philosophers. He wrote the same in his introduction of The Virtue of Selfishness, where he also says that Ayn Rand advocate some categorical imperatives. Clearly, he has never read Causality versus Duty.
And it's always like that : He regulary sees "contradictions" in Ayn Rand's philosophy...grounded on his own misunderstanging or ignorance.
As he is the only French voice, visible in the media, who talks about Ayn Rand. Many French people learn about Ayn Rand through him, i.e. through his errors, his fallacies and his superficial understanding. I think that there is no one who does not harm Objectivism in France any more than he does, though I'm pretty sure he views himself as a fair spreader of Ayn Rand. He is also very critical of the Objectivist movement.