It would be easier to undo damage when an abuser is invited to a group if a new chat could be created from the member list at an earlier point in time.
The Clone chat feature may be ineffective if it is pressed long after many members have been removed by the abuser.
Sounds too complex to me TBH. Seems like an XY problem.
the other way to look at it, this is a remake the room function when a troll is removing everyone
if i am removed after the troll 
removing many people before me, re-adding people is troublesome 
even with Clone Chat function
Internally there are addition and removal timestamps sent around for synchronization, so something like “add everyone who was removed after this timestamp” or “remove everyone added after this timestamp” is not impossible.