Could you explain the terms you're using here?
- What's an OK MOVE?
A move that works, that is, it's allowed by the system. Moving a page to a nonexistent page is an "OK MOVE". Moving a page to a history-less redirect is usually an OK MOVE.
- What's a BADMOVE?
A move that doesn't work: failed move, can't do it, that sort of thing. Should have said failed move or something. Moving a page to another Article with a history is a BADMOVE.
Page A ---BADMOVE---> Page B (history-less redirect to page C)
- How does a page C come in on BADMOVEs?
Page C in the example you cited is just some random page the redirect points to. It's important to distinguish between page B and page C the same way this works:
Penguin is an article Phoenix is an article Ice Bird is a history-less redirect to Penguin Fire Bird is a history-less redirect to Phoenix
You can move Penguin to Ice Bird but not to Fire Bird. Phoenix is our "Article C"
Hope that cleared things up.