I suppose Finnair can set the rules about fuel surcharge any way they want. Unlike the taxes etc, as those are not actually payable by them if the pax doesn't fly. Whether it is ethical is another question.

KLM has started doing the same some time ago.

I wonder how this works for award flights though (can you cancel those and get a point refund in the first place?)? I'm not using my AY account any more, so not relevant for me.