Going on a witch hunt to identify an employee who went through the trouble of speaking anonymously sounds like a bad idea.
If the only course of action is to say "Oh no! They used a throwaway account, so there's nothing we can do about the toxic environment posts like this create for members of our community!" that doesn't bode well for having a non-toxic environment. And since I do need to disclaim that I am a MoCo employee (but 100% speaking for myself alone), I should also mention that you will find in that list of posts a link to https://www.reddit.com/r/MensRights/comments/35u1yp/an_email... where the contents of a Mozilla Corporation internal-mailing list post were reposted. So even if one wanted to write this off as just a random internet troll, the situation is that there is either a MoCo employee intentionally harassing another MoCo employee and Mozillian or a MoCo employee passing information to someone doing the same thing.
I do want to be clear that I am not attributing these hypotheticals to your one-sentence reply. But I also want to be clear that we can't write off this type of toxic behaviour as acceptable because of the risk of being perceived as engaging in witch hunts/star chambers/other hyperbolic misapplications of known-bad-terms.
How on Earth was that comment "creating a toxic environment"? It was added a week and a half after the original post went up. By that time nobody but the most obsessive are still reading the same Reddit post.
Calling it "toxic" and having the CEO himself declaim from the pulpit about how this random throwaway account on Reddit with all of six posts to its name over the span of three months must be destroyed seems like using a nuclear weapon to kill a fly.
I'm not gonna argue what side this is on, just that there is there is a floor. They're called "haters." Conventional wisdom is to shake it off. (Just think about the time spent getting down and out. You could have been getting down to sick beats.)
Different people will have different opinions on if this is above the floor and actions should to be taken in response. People are going to to disagree about when actions cross boundaries, so simply labeling actions as harassment doesn't cut it to make everybody agree with your view that it has crossed boundaries.