Careful that a closed source python implementation not seize this opportunity to move ahead with features, forcing others to follow along in a way that is difficult to do (because of closed source).
I don't know if ironpython is closed or not, but Microsoft is hypercompetitive and leverages their monopolies to create instant market share in new markets. Then they use closed source extensions to create a situation where they take the lead as users find that it's best to use their language impl with extensions instead of a language impl without the proprietary extensions.
Slowing things down would allow the market to be seized by a closed source vendor.
Of course, if there is a technical real reason not to want to add features, then that is another story.