This is why journalists try to get multiple sources to corroborate what the other is saying.

That's hardly very likely with whistleblower stories, all you can do is be careful with wording like "<name> claims" "<name> alleges" to qualify the reporting. I read Krebs I find it hard that he wouldn't retract something if Ubiquiti (or someone else) came to him with evidence showing the "whistleblower" was a fake that he wouldn't retract the article based on new information. He seems like a good journo to me and has nothing to lose by doing such. He reports on a lot of stuff and now one is going to be constantly fact checking every story they ever put out there. It's impossible. I suspect Ubiquiti filed this before they ever contacted him about the whistleblower being a fake.

The story already went forward.

It means that a correction should have been issued.