that was my same feeling. I'm a C# developer, and even though I consider myself a decent dev, I never thought of C# as a toy language. I guess I'm not that good.
Until the author has made systems like Stack Overflow, Exchange, IIS, Office 365, and SharePoint in C++, his comments about C# being a "toy language for small projects" are pretty much baseless. In fact, this entire article is nothing more than an academic exercise, he has no practical examples where any of his concerns had a significant impact on a production system.