I understood the quote as an anthem for objective thinking. Of course SJs may be according to the definition on the inside be conventional but they have to find, like everyone else, a working interface to submit their own world to the One around them. If this world is more made for SJs and due to that they have an easier way of telling what they feel is another point to argue and I am not really unfair enough to say that.
If you, for example and for the sake of archetypes, have a tinkerer live in a dessert, a knight having to wear size XXL and a druid living on the moon; the tinkerer will never be able to find enough ressources to craft, the knight doesnt fit in any common armor and the druid cant smoke marijuana.
In the light of that, I dont think that you can just say SJs are the societies conventional-thinking role models and never are eccentric.
I tho liked the quote as I said, as an anthem on objective thinking. But maybe I am far of the scale here