I did not know I can also claim in addition for the miles on the rerouted airline. Thanks for the tip.

I agree also that any confirmation from ground staff is itself unreliable. I don't think I mean it as an absolute right but what I mean is more a springboard that you can go crazy on in getting something in return further down the line.

Probably the conclusion now is if you get downgraded on your next available flight and you voluntarily take it instead of waiting for a J class seat, you waive the right to claim for points and miles accorded to the original ticket.