Re her 'niceness' or lack of it, none of us know how nice or not she is in real life, and frankly, it's irrelevant. If she's interviewing someone who's had a terrible time, she's paid to 'be nice' to them, whether she feels compassionate or not.
I work with people, some have mental health needs, some I dislike, but I'm paid to be compassionate, supportive and equal in how I work with everyone. So that's what I do, does that make me 'fake'?
Niceness, real or not, is just a non-starter of a criticism, true or not.
As to whether she 'knew' or not, anyone who's not closely investigated it has no idea what she did or didn't know. As an example, about two decades ago I worked in a team of about 10 people, it was an intense job and we were very open and honest with each other about our lives and feelings, not something I enjoyed tbh, but it kind of helped, I think.
Anyway, that's not the point, the point is that it was 'common knowledge' in another team that two of my colleagues were sleeping with each other. They weren't/couldn't be for various reasons, rotas, hobbies (me and one of them did a sponsored bike ride on one of the weekends they apparently went away together) but not least of all the sexuality of the woman concerned being utterly incompatible with the 'known' relationship. Still, everyone outside of our team 'knew' it was true.
And then, a decade later we found out that two other members of the team were having an affair. None of us knew, none of us thought they were anything but friends.
My long-winded point is that regardless of what outsiders like us may be certain that we know, that people closer than us must have known, that previous patterns of behaviour must indicate is true... the thing is that we. don't. know. what. she. knew.
She may be an awful person who knew every facet of what he did, or she may have been successfully blindsided and lied to or she may have had suspicions but avoided them out of guilt, out of cowradice, out of career pragmatism or out of diplomacy. Again, we. don't. know.
Yes, this is a discussion forum, but there's times when discussion morphs into plain self-righteous gossiping