Yes, but betting on Python is the whole point of PyPy. The idea is to build a toolchain using a relatively high-level programming language like RPython to build new languages.
As far as I understood is that this allows for low-level concepts to be changed more easily, while low-level implementations always suffer from basic decisions (e.g. you will never get reference-counting out of CPython, while you might be free in to change that in an RPython-implemented language).
So, the entire point of PyPy is being able to implement other high-level languages in RPython, so an attempt to implement Ruby is definitely very interesting! Also, the resulting binary is not depending on Python whatsoever.
As far as I understood is that this allows for low-level concepts to be changed more easily, while low-level implementations always suffer from basic decisions (e.g. you will never get reference-counting out of CPython, while you might be free in to change that in an RPython-implemented language).
So, the entire point of PyPy is being able to implement other high-level languages in RPython, so an attempt to implement Ruby is definitely very interesting! Also, the resulting binary is not depending on Python whatsoever.