The problem is that his journalism
was not vindicated. It was supported after his death by the same people who supported it when it was first published.
Maxine Waters made partisan hay out of Dark Alliance before the story was vetted by any other news paper (and more power to her! I don't like Waters, but I'm on her team politically).
Too, Robert Parry defended the story immediately after it was published. Parry is a very reputable journalist, but if you can find the piece where Parry connects the dots this eulogy does, I'd really like to read it, because all I can find are places where Parry writes, in effect, that the government isn't trustworthy and thus a story like Webb's is plausible.
But nobody's argument is that the story is implausible. The problem is that the story isn't reported. There aren't facts that back the accusation up.
It's even worse, because this eulogy doubles down on Webb's original argument. The dodges employed by The Intercept and the rest of Webb's defenders are that Dark Alliance is "true enough" --- that CIA-backed paramilitaries were involved in drug trafficking, and the CIA knew it. But that's not what Webb argued. He made a stronger claim: that the CIA knowingly allowed the Contras to ignite the cocaine epidemic in the US. Even The Intercept isn't willing to back that claim up --- but this article, which you're pointing us to as further context for the story, does.