That has been pretty much grounded for years, I guess the MoF Seattle has just made it official.
They also own the B-17F that was airworthy when they got it, and I believe they also have the last flying DC-2. And many of their fighters were airworthy (but rarely if ever flown) when they were part of the Champlin Fighter Museum in Arizona.
In short, like many others, the Museum doesn't fly their aircraft
I believe we're going to soon hear of another type which will be permanently grounded when the last flyer goes into a museum.