The real reason that people are afraid their theories are "being bashed with intolerance" is because those same people who put forth those theories are making some rather grand assumptions, most specifically that Slytherin=evil and bad, and that if you have a 'good' character, they can't be in Slytherin. And because only Gryffindor is good, your 'good' character MUST be in Gryffindor.
Quite frankly, some of us, myself included, find that sentiment offensive. And after several years of the same statement being thrust at me, ti's beginning to get obnoxious.
Further, making a character like that go against everything their entire family has ever stood for is bordering on the very definition of Mary Sue/Gary Stu.
It's also "easy" and "lazy" writing. Instead of working with what you have (i.e. - a character who is mostly undefined but almost guaranteed to go to Slytherin) with the traits they almost certainly have (clever, cunning, ambition, most likely a blood prejudice, even if he keeps it hidden) and making THAT character fit in to your story, it's "easier" to just make him something completely unrecognisable and throw him into Gryffindor, where all the good folks are anyway.
Draco and Astoria would not say "don't get into Gryffindor, that's where all the good people go". They would probably say "Gryffindors are blood-traitors." And they would probably denounce Hufflepuffs as Squibs and Mudbloods (although why this is the overriding prejudice in the Wizarding World, I have absolutely no idea. )
Narcissa and Lucius would back them on this, and most likely Astoria's parents and sister as well.
Now, I think the Malfoy family is CUNNING and savvy enough to let their own prejudices lie low when the political climate is not condoning such beliefs. They would not be out declaring "Down with Mudbloods!" and demanding registration for "undesirables" or anything ridiculous like that. However, in the privacy of their own home, I absolutely believe that they will teach their children that they are superior for many reasons, among which is bloodline.
As for their financial situation, yes, I think they are quite well-to-do. Some fics are insisting that the entire Malfoy family fortune was seized after the war, which appears to be completely wishful thinking. (It doesn't bother me so much when the writers under age 18 do it, but the writers over age 35 should know better!) Not only is there nothing in canon to support it, it's preposterous to believe that the several thousand year old Malfoy family fortune wasn't diversified into various funds, accounts, and off-shore locations to prevent such a thing.
Yes, I think Scorpius is even richer than Draco was. Not only does he have the Malfoy and Black fortunes coming to him, but also the Greengrass fortune. And even if every single Knut the Malfoy family had in their various Gringotts vaults was seized by the Ministry (something I find completely improbable), there is a saying that "compound interest is the most powerful force in the universe", and the accounts they most assuredly had not only off-shore but even in the Muggle world would easily maintain their standard of living. In fact, i think it's quite likely that Lucius moved the vast majority of his investments off-shore once he was released from jail, and quite possibly as soon as the Dark Lord was resurrected.
Also, remember that Narcissa was a loving and devoted mother who doted on her son (she sent him large packages full of candy every day) and looked the Dark Lord in the eye and lied to His face to protect her son.