When people die they go to SS. Why is it so much of a surprise that powerful dead humans(the Fulbring) would end up in SS?
That is not what the mockery is about. Why bring them back at all ? If Bleach history is any indicator they will meet the same fate as the arrancar bitch trio.
I also find it odd that they have the same outfits, and don't look like they have been assimilated into the Shinigami forces. Isn't that what happens with people that have reiatsu in SS ?