Remove co-author for ethical violation? My co-authors and I are preparing to submit a major project manuscript.  Unfortunately, we have just learned that one of the persons involved in the project has committed major scientific ethical violations related to the project, but not directly impacting this paper.

The scale of the ethical violation is quite large (think: non-consensual and dangerous medical experiments) and is directly connected to their work on the project. It does not, however, affect the validity of this manuscript or their contributions to it in any way.

Many of the co-authors, however, no longer want to be associated with this person in any way, and are likely to withdraw their names from the manuscript if this person remains an author.

Would it be reasonable to remove this person from authorship based on their ethical violation, essentially as a form of community shunning?
Personally I think you cannot do it, and I wouldn't even speak in terms of "reasonable" or "unreasonable". If someone makes a contribution to your work, that person is your co-author, deal with it. If a person wants to remove his/her own name, its their private decision, but I can hardly imagine doing that for other contributors without their consent.

When I engage in research with other people, I consider it a sort of binding contract: I do this for you, and I expect you to put my name on the front page. If you don't want to deal with me anymore, it's OK, but next time, not this time.

Furthermore, while I don't want to overthink it and portray pictures of possible dystopian future, I believe such ways of "community shunning" are very dangerous. Maybe today you have a valid reason for it, but you'll open a Pandora's box: first we retroactively remove people for their flaws, then for their views on sensitive topics, then for their thoughts.