That is actually not a new move for comics. Both DC and Marvel have de-aged characters but still maintained their full knowledge of their lives. They pulled that with the Atom back in the 90s and even had Ray Palmer join the Teen Titans, but with him remembering having been on the JLA. I'm sure it upsets some people, but its bound to piss less people off then straight up saying that everything the fanbase has read up to a certain point no longer counts.