I can steal a can of Coke Zero from the corner store, but it doesn't mean I won't have to pay the cost if they take me to court. Or if a regulatory body steps in.

The US and EU have both unequivocally stated that refunds are required for any cancellations, if the passenger rejects other offers.

If the UK is still subject to EC261 (I am not sure, but I believe they are), then what AC is or is not doing is irrelevant.

Unless an airline says "cancel today for full refund", or your fare rules have different refund penalties dependent on time before departure (I know CO fares have different change penalties), there is never any benefit to cancelling until 2 hours before departure.