If it wasn't a valid filter, it might have moved somewhere else in the list, which would make it harder to find
The selection moves as well however, you never need to find the filter you just edited.
How about using this interface, and using the inline tag editor when a user selects a filter on the list to edit, but having a 'Filters->add filter' menu option that opens a new dialog box?
Sorry, that's a horrible idea. Opening new dialogs should always be prevented whenever possible.