This is exactly the kind of thing Mozilla should be working on, in my opinion. It's enabling something new to work in a browser, and if Mozilla didn't do this Google would have, only it would be locked into Google Sheets or something.
Why should Pyodide or the whole Iodide project be any different. Other than Firefox, Thunderbird and MDN, only Bugzilla and Rust really stands out as successful projects, and that's only because they've been developed to solve an actual problem.
I'd be surprised if the Iodide project will see any real usage 5 years from now. Are any data scientists really look to move to a browser based workflow?