The claim was that Rust made making something parallel easy/easier, and the illustrative example given was someone trying to parallelize something in a game engine. Whether Rust is good for game development or not is irrelevant to the point that was being made.

Even if everyone accepted that Rust was horrible for game development on most metrics, the example given would still carry the exact same weight, because it's really about "parallelizing this would be very hard in C++, but it was very easy because of Rust."