Imho all transactions with the stolen tokens should be voided.
Bittrex is definitely able to provide a detailed trade history.
It's like a thief stole bunch of limited collectors watches from a watch store, hastily selling them for cheap and the buyer says: "I can assure these new watches in my possession aren't going to leave my hands any time soon. So this is a nice gift for me, and you can rest assured that the collectors market will be unaffected."
The only problem is that the watches (Tokens) are still property of the watch store (Agoras devs).
I am also disappointed that they fell for such a scam. It highlights once more the weaknesses of the current organisational setup and business end of Agoras. The good thing is that the scam was early in the lifetime of Agoras, so it's impact can be unscrambled relatively easy. There's no telling what would have happened if such a thing took place later with actual trade volume and thousands of transactions outside the exchanges. One should keep in mind that scams and security breaches are the number one killer for crypto currency projects.
As part of my due diligence on Agoras, I wrote to Poloniex two weeks ago asking them if there had been any communication whatsoever taken place between Poloniex and the developers of Agoras or any other affiliated person.
Mar 21
Thank you for contacting us about your request and do apologize for the delayed reply. You can request a coin to be added to trading at
https://poloniex.com/coinRequest. Fill that out there and it will be reviewed; coins are reviewed on an ongoing basis once added to the request page. It is not voting so multiple requests will be ignored, there would not be any contact to the poster nor the dev team if the coin would be added or not. We thank you for your submission.
Best regards,
Maurice
Poloniex Support
This was actually the only red flag coming up and I didn't pay much attention to it, since all the other stuff I checked turned out to be true and made sense.