In all fairness I've only seen the musical, so the book might have some nuance I'm missing, but it seemed to have a very pro-Christian message, with the only positive figures of authority being priests and nuns and a very central theme of repentance, forgivance and atonement. Was the Church so pro-Monarchy back then?
You may be interested in this answer by /u/bluerobot27 : https://www.reddit.com/r/AskHistorians/comments/4pf5r5/why_was_les_miserables_banned_by_the_catholic/