I do not believe any human will or would be able to contact all places trading XEM before said coins are moving? (if true what I'm reading here - that there are stolen funds)
There aren't many XEM exchanges. All of them will have contacts with the NEM foundation. They would've needed to be to create their back end stuff. A few messages will lock the hacker out of all exchanges.
Oh I see. Then again, if true, that is a dangerous level of centralization.