Most people talking about C# and Java, they refer mostly to application development. You rarely hear these languages at system programming (doable, just rare). Rust is at C/C++ level when it comes to system programming and eliminates a lot of C/C++ issues and yet added features found in Java and C#, and even Haskell. People just don't know a lot about Rust to criticize upon and yet seeing it mentioned everywhere. I can understand if some feel a bit "fed-up" seeing Rust brought up in a non-Rust thread. But I do agree with you, Rust is very relevant for discussion here.
The article title is "Why is C Faster than Java".
I would expect to see Java, C#, C, C++, and Rust mentioned quite a bit in the threads here. It's all relevant.
Rust's primary language feature - the borrow checker - is about adding compile-time checks on resource management(mainly memory), and the original article talks about boxed vs. value types being a major source of inefficiency.
So talking about Rust in a comparison of C and Java mentioning memory indirection bottlenecks seems about the most relevant place to discuss it.