I was kind of wondering that too. Perhaps for sandboxing, but then i wonder why not something like webassembly or even eBPF. I kind of wish the author went more into the why of it.
Nothing wrong with using WebAssembly, if you wish to. eBPF I'm not so sure is a good fit. Most people are just fine with Lua, LuaJIT or Luau though. This is really just for especially interested, or if you really need low latency.