Earlier quoted context omitted.
Why is it unreasonable to expect the RubySpec dev to do additional work, but reasonable to expect additional work from the MRI devs to comply with RubySpec? I get that "the implementation is the standard" is frustrating for people who want to make an alternate implementation, but why should that obligate the original developers to accept some third party's definition of what their project should be?
It's not a third-party definition, it's their definition, should they want to contribute to it. By writing Ruby specs you're defining Ruby.
And presumably the MRI devs would say that by coding MRI you're defining Ruby. What gives RubySpecs the authority to say they are the canonical definition of Ruby and everyone should follow it, when the people who created Ruby disagree?