If they pardon him that doesn't mean he will or has to go back to the US. Also your ""feelings"" argument can easily be refuted: A) There are proves that he did use the official channels first. B) This isn't even a moral but a legal concern. C) You can excuse participation in the Holocaust with it.

I see where you're coming from, but you can spin it either way. What I think they should to is to use the pardon to gain trust and create anonymous contact points so that whistleblowers will use the official channels first.