Got this reply from SAS:
We are writing to you regarding an online cancellation form that was sent to us.
The unwanted segment(s) will be cancelled, and refund will be processed when journey is completed.
The refund due will depend on the restrictions on the ticket you have purchased.
Does that look right for cancellation due to involuntary change? Seems like this should be refunded now (and not based on the original rules)?
P.S. Called. They say that it was processed correctly and refund for the return flight will be made after the outbound is flown. Strange, but ok.