It's also worth remembering that this is just a game, and as such it's somewhat of an apples-to-oranges comparison. Java's RAM usage may not be impressive compared to C, but that doesn't make the results overall any less impressive, especially knowing what it was like before those 20+ years of effort.
I don't see a reason that both Rust and Java's results can't be impressive in their own right. Java's numbers are (for the most part) impressive compared to C and Rust's numbers are also impressive compared to C, just in a different way.
