Yes, that's what I meant by "we have a defence", I did understand.

I've read the on-list discussion but I'm still not convinced it isn't better to just pay into hash-covered addresses, now, and then go forward from there. As you point out, you need a flag day after which every tx must be delayed N blocks (and we have to have consensus on which outputs that applies to; perhaps, easy). Your proposal needs QR outputs to already exist, needs consensus on several details even if a soft fork. And it's at least very weakly confiscatory, which makes consensus super-hard.