When I read the article, I didn't know it was written be Stephen Wolfram. It sounded like any other math/tech blogger. He'd played with these things when he was younger, similar to what many programmers have done. And he was excited to find something familiar on a public building. It sounded completely non-arrogant to me. I used to play with fractals and would be just as excited to see my familiar toy on a public building, even though I didn't discover them.

He didn't claim to have invented it, or that the building was designed in his honor. I think you have to be expecting arrogance to see it in this article.