Ah yes--that is more what a meant, so then I agree. Slughorn is not unaware of the changing times and while he may never have had a problem with Pureblood Supremacy before, he's not that way now. Unlike, say, Lucius, who would resent the change in attitude (and Lucius is not young enough to have been brought up in the same way).

It's just--as you said--this is probably the most we can expect from him. Not because he's a terrible person, imo, but because (and this is more my point in bringing him up), he's old. The books just aren't going to really focus on Slughorn's change in attitude, which wouldn't have as much impact on society. His main power now is the affect he has on students, many of whom are already far beyond him in terms of their mindset because they were born later.