More the overuse of his name to name other things and the fact he has been talking about revolutioning science for at least 2 facades without doing it.
I think it depends what you mean by arrogant. To me, naming things after yourself is a bit of vanity. But I also see the advantage of building a brand with a consistent meaning. You may not believe everything Wolfram has to say, but I think that the naming here conveys a clear meaning to users.