If you know that you received extra money, I think you have a moral responsibility to try and return it (maybe minus a few percent).

However, in this case:
- You can't return it to the rightful owners directly.
- Nefario is obviously very incompetent and untrustworthy, so it would be reasonable to think that returning the money to him would not get the money to the rightful owners.
- Nefario is holding hostage your assets and the BTC of most users, so I think you would be morally justified in refusing to return the money until those things are released.

So I'm certainly not going to give recipients of the extra money scammer tags at least until Nefario releases most of the BTC and asset info.