I'm pretty sure it was just snark at Javascript/ECMAscript. IMO it's pretty hard to justify calling it a legacy language when there are 4 major JS JIT engines

I'm pretty sure it was just snark at Javascript/ECMAscript. IMO it's pretty hard to justify calling it a legacy language when there are 4 major JS JIT engines actively competing for performance, and a pretty thriving developer ecosystem. It's about as young as Ruby, and younger than Python and Haskell.