I think think that’s a good default for the Offtopic category, but we would still want an “offtopic or unfocused” flag (replacing the current “offtopic” flag) that would start a timer (possibly a shorter default timer for posts that were specifically flagged, e.g. 48 hours) and can be applied to posts in any category without moving them.
Otherwise, I’m worried that Offtopic will just become a dumping ground for annoying threads. e.g. “How can machine learning be better in Julia?” clearly belongs in Specific Domains / Machine Learning if anywhere, but is also such an unfocused topic that it will never end without a time limit.