It does warrant a public apology.
The thread did more than just insult Puffin. It created the illusion of a conflict ridden environment where a generality of "people" are upset. In reality I bet it's only one or two.
But that illusion that it's some silent mass of people can really mess with someone's head and affect future endeavors to the detriment of the majority of players who don't, and never have, felt that way. And by taking the criticisms public instead of having the guts to deal with it one-on-one, in private, now some players might wonder that while they're having fun, is the person next to them having fun or are they one of "the ones"?
Honesty I see no reason to have put Puffin on blast in the first place unless you were hoping to get tons o' upvotes or some sort of validation from the community. "Going public" is brave when it speaks to unfightable corruption and power, but is cowardice when it's done to avoid private confrontation and I just saw it as an effort to try and create the very "upsets" you claim already existed with "people" so you might see the change you, and you alone, hope for.
So a public apology is warranted to address the bigger issue of having wove a hostile climate by hiding the identity of accusers and being general and non-specific in claims. In the end, what was done wasn't just "make Puffin feel bad", and the impassioned responses from people who aren't Puffin proves that.
That being said: I have never been in a GM scene with Puffin, but I have gotten off screen action responses. They have always been creative, detailed and always provided me material to work with. Even when a I was brand new and didn't put in any expectations or much detail in terms of what my character was trying to do or why. I am sure it was frustrating to work with such scant detail and a pretty awful grasp of story from a newbie at that time and yet I always got something awesome. I think it's clear enough how much effort she really does put in to telling a story and trying to make sure everyone has a great time and so other players will take offense at anything threatening that.
