I think he shows the performance of running JRuby on top of GraalVM. GraalVM uses Graal (the JIT compiler) in place of C2 (the JIT from HotSpot).
But TruffleRuby is something different. It is another Ruby implementation (just like JRuby is a Ruby implementation) using the Truffle framework. And Truffle framework requires to be run on GraalVM.