I don't really think it was an arranged marriage, but given that I read on the lexicon that Daphne was a suspected pureblood (something about Rowling saying the name was or something but it couldn't be considered completely 'canon'), meaning Astoria would be I could maybe see it being a 'supported' marriage. Like Lucius being "Oh, Astoria is a nice girl, you should date her" or something

I also think that he'd be more leniant with Scorpius, but I could still see him being annoyed if he hooked up with a Muggleborn, being his bringing up.