I didn’t think Mr. Bennet's comment ending Mary's recital was all that bad. If you want to find fault with him, do it for failing to control his wife. Her behavior was horrifying. She spoke "freely, openly, and of nothing else but of her expectation that Jane would be soon married to Mr. Bingley [when they weren't even courting]," loudly "enumerating the advantages" of the match within the presence of Darcy. imo she bore the greatest responsibility for Jane's heartache.
Mary's behavior was rude and in poor taste, but at least she didn’t say anything personal about the Bingleys.
