That is true, but remember that VMs for languages like Python, Lua, etc. are written in C. That means you can compile them to asm.js. There are demos of this (using emscripten, not asm.js) from a while back.

If you ported a VM with a JIT, and added an asm.js backend for that JIT, it could be a very fast way to run basically any language in asm.js.