The response by Uber is not consistent with her claims being outright false. The investigation in question is not about putting Susan Fowler on trial, but about determining whether there's systematic or cultural issues that fostered this kind of environment.
Susan made mention of many points of evidence that would be easily verifiable by Uber - if she were lying about those it the tone coming from Uber would be completely different.
An employee made a claim that Uber is intentionally covering up sexual harassment. The CEO of Uber is now investigating the validity of those claims. I agree this is not about putting Susan Fowler on trial. It's about finding the truth, and we have Susan Fowler to likely thank for pointing us in the direction of that truth. The nuance I'm trying to point out is that knowing what is true still requires actual evidence. I see a lot of people coming to the worst possible conclusions about Uber without said evidence, and I find this concerning. Seems more like a mob mentality than a group of rational people trying to find the truth.
In this case I think the evidence is actually Uber's lack of rebuttal (admission by omission). For example, searching the slack logs on the first day of Susan's employment should literally take less than a minute. If there was no proposition there, Uber would have made a press release stating exactly that a day ago. They haven't. The logical conclusion here is thus that the evidence you want exists and Uber isn't (and probably won't) releasing it to the public.
Put another way, what guarantee do you have that Uber will actually provide the evidence you're seeking one way or the other? On one side we have a claim made by a former employee, backed by "that doesn't surprise me" anecdotal stories from current and former employees, and on the other side we have... a promise to investigate internally using a highly biased team. It seems to me you're kind of looking for a courtroom-level burden of evidence that simply isn't realistic to expect in this situation.
Susan made mention of many points of evidence that would be easily verifiable by Uber - if she were lying about those it the tone coming from Uber would be completely different.