Speed is not a feature if there isn't even syntax parity with CPython.

Not having parity is a property they want, similar to Starlark. They explicitly want a less capable language for sandboxing.

Think of it as a language for their use case with Python's syntax and not a Python implementation. I don't know if it's a good idea or not, I'm just an intrigued onlooker, but I think lifting a familiar syntax is a legitimate strategy for writing DSLs.