Antonia, and all
I've stumbled upon this notability issue again and again since the early days of Wikipedia, and after almost twenty years munching on it, come to the following conclusions.
Notability is defined in WP rules from an apparently technical and non-moral viewpoint. Someone or something is notable if it has been noted (so to speak) in some reliable sources, preferably several independent ones. Wikipedia editors don't judge why someone or something is notable, they simply take notice that it has been documented somewhere, and this documentation is gathered in an article. Notability and NPOV (neutral point of view) are the two pillars of Wikipedia deontology.
If you accept that Wikipedia is the master of notability in Wikitree (as seems the rule if I'm not misled by what I read), you have to bind by its rules, with all its consequences, including mass murderers being notable. Notability Wikipedia-style is totally amoral.
Or so they say. If you look carefully, there are a lot of known biases (gender, social, ethnic, political ...), on which WP line of defence will be usually "non guilty" because they say they just copy the biases of available documents.
If you ask me today, I would say a base like Wikitree should get rid of all this notability categorization altogether. Notability makes sense for WP, despite known biases, because you have to set limits on who is allowed to have an article in WP or not. Notability there is a question of who's in and who's out.
Here in Wikitree there is no problem of the sort. Every human is welcome, as I understand. Hopefully we are no more in those aristocratic families where the "infamous" for any reason are kicked out of the family, and of the tree. The criteria of inclusion is being a human, and we all have saints and criminals in our ancestors.
This kind of affair should lead us to the conclusion to get rid of notability altogether, both good and evil. Having a link to a Wikidata article when there is one is OK, or to the Wikidata identifier, or whatever external identifier leading to external data bases for complements of information.
For what it's worth ...