Yes, it is damage control. That’s OK.
The whole point of spreading the word about an incident like this is to get public attention on it, and make the company realize that the way they’ve handled things was bad.
A letter like this indicates that they’ve realized they fucked up and they want to do things differently going forward. That doesn’t mean they’re suddenly trustworthy, but it does mean they can be negotiated with.
The correct response is to accept the offer of working together. We want to encourage companies to be cooperative and discourage insular, proprietary behavior. If you slap away the offered hand then you discourage future cooperation, and now you’re the roadblock to developing an open system.
When you start getting the results that you want, don’t respond with further hostility.
And even if the cooperation doesn’t last, it’s an opportunity for the open source developers to work with the product engineers and get direct information from them right now. There’s nothing as valuable as talking to the guy that actually designed the thing, or the guy who can make changes to the product code.
Even if that relationship doesn’t hold long term, the information gathered in the short term will be useful.
If I were part of this project this is what I’d be going for. Push the company to give you direct contact with the relevant engineers, right now while the negative public opinion is fresh and they’re most willing to make concessions, and then get as much out of that contact as you can. Take them at their word, make them actually back it up, take advantage of the offer to cooperate. Sort the rest of it out later.