If I tell you the sky is green the best way to refute that to your audience is to ignore me entirely as a person and instead tell people to go outside and look up: Show them some evidence and factually refute my claim. You don’t say “this man isn’t a sky expert, has never spoken to sky experts, and should therefore be dismissed!”

The parent comment’s point would seem to be that this person is making a claim that should be refutable with evidence. But the evidence is Facebook’s own data supporting her claim so they can’t do that. Instead, they diminish her credibility. It’s not “smearing” in the sense of calling her a baby eater, but it is a credentials fallacy meant to make people dismiss her claims regardless of validity.

No, they are all ad hominem attacks. She shared ~18000 documents. Doesn't matter who the messenger is at this point, it's all about the veracity of the documents themselves.

Did Facebook deny creating those documents? No. Did they refute statements from those documents? No. Hence statements about the whistleblower are not relevant.

they're not relevant at all because you don't even need to work at facebook to disseminate facebook's research. It's a smear because it's a completely irrelevant ad hominem. The research is straight forward enough, and now public, so that everyone can actually come to the exact same conclusion she did simply by reading it. What she has done is made it public. And Facebook does not refute is because they cannot, so they go after the person's CV.

Can you explain to me using basic logic what the connection is between your career status at facebook and reading research of the effects of facebook products on its users? what's next, do I need to work at Exxon to understand climate science?

How are they relevant?