Well Solas does ooze elitism even when he tries not to. As compared to Viv who never tries not to 
Its like he only considers emotional connection from a theorical stand point in others.
He definitly gets taken by surprise by the emotional benefits of a relationship. Thats usually the type of answers you get from him when you choose romantic dialogue after major quests (im not used to having someone there for me, etc.) She is his connection to the present, she makes things matter (and thats against the Plan).
Solas definitly doesnt have the right attitude to convince people. But I find him much more agaisnt acculturation then pro-racism.
He also is an ass to Sera just because he can. That makes him a troll ;P
It's just as likely that he really has been alone for a long time and really isn't used to having someone there for him, especially someone in the current world where he's considered kind of nuts by a lot of people. He had a close relationship with Mythal, after all. His friendships with spirits aren't quite the same but they aren't nothing either.
He's only against acculturation in the context of Sera being basically a human with pointy ears. When he says he thinks the Inquisitor's race is thuggish, that isn't being against acculturation.
Yeah. Sometimes he's trolling her. Sometimes he's saying, in all seriousness, that she's "the furthest from what she should be." At the end of a conversation, like a judgment, rather than at the beginning as an attempt to draw her into conversation.