He is doing a piece about the departure of our founder and the subsequent exodus of engineers. I was part of that exodus and had a pretty negative experience. I can't see any advantage to talking about it though.
Write it down and save it up into a book you might write one day.
Even if you have no idea of writing a book now, writing it down now would probably encapsulate a bunch of details that will have faded years from now. And at that point you'd be in a good position to decide to share it or not.
A vindictive employer could sue you for defamation. I really don't see why you'd take that risk.
Does the company have Glassdoor reviews? Are those reflective of your experience? If so, then there's a warning to new hires out there already, at least.
Exactly. If a future employer types your name into Google and reads this article as the top hit, would you be okay with that?
If this reporter is talking to other coworkers of yours, you may also find out some information you weren't expecting to hear, or prepared to learn. Are you okay with that as well?
I wouldn't, in case someone not liking what you've said has money and chooses to get legally unpleasant. Years hence, you'll have a fund of after-dinner stories to tell instead.