Of course SA's concern is that AIs would override difference. Overriding difference means less freedom. [...]

I question the accuracy of your mental model of Stuart_Armstrong, and of your reading of what he wrote. There are many ways in which an insufficiently friendly AI could harm us, and they aren't all about "overriding difference" or "less freedom". If (e.g.) people are entombed in bunkers, lobotomized and on medical drips, lack of freedom is not their only problem. (I confess myself at a bit of a disadvantage here, because I don't know exactly what you mean by "overriding difference"; it doesn't sound to me equivalent to lacking freedom, for instance. Your love of neologism is impeding communication.)

why isn't he concerned with our current system?

I don't believe you have any good reason to think he isn't. All you know is that he is currently posting a lot of stuff about something else, and it appears that this bothers you.

Allow me to answer the question that I think is implicit in your first paragraph. The reason why I'm making a fuss about this is that you are doing something incredibly rude: barging into a discussion that has nothing at all to do with your pet obsession and trying to wrench the discussion onto the topic you favour. (And, in doing so, attacking someone who has done nothing to merit your attack.)

I have seen online communities destroyed by individuals with such obsessions. I don't think that's a serious danger here; LW is pretty robust. But, although you don't have the power to destroy LW, you do (unfortunately) have the power to make every discussion here just a little bit more annoying and less useful, and I am worried that you are going to try, and I would like to dissuade you from doing it.