From what I can tell the "tar-and-feather thing" is outrage directed at Slack and its CXOs, rather than the poor guy who happens to be reposting a message from the CPO.
Please don't let your moderator's concern for injury to individual people blind you to the fact that the outrage triggered by outrageous conduct is directed at the outrageous company and its officers, rather than at individual folks who aren't in a position with any real power.
I apologize for using your comment as a place to hang a whole generic thing about mobs and whatnot—I certainly didn't mean it about you personally (or even your post) - it's a shared group phenomenon for sure, and I could have made that clearer.
In my days of heading R&D for a regional social networking site, we discovered that first ~100k of our users were both the most valuable ones, due to the extent of their interaction with the site, and due to the fact that their risk tolerance for our /new/ product meant they would also tolerate future products. As such, that "first wave" of community around a product - is - the wave the creates the market for the product.
In case of Slack - they were taking that goodwill for granted. And the community's outrage called that bluff. It highlighted to other readers (like myself, I don't use Slack anymore so never paid attention to the ownership change) that it's now part of Salesforce (and that's a negative signal for me, might be positive for others); that it got pretty dubious business practices (as others in similar situation to OP have spoken up); and that none of the CXOs' committed to meaningful (from my and community's perspective) responses - post mortems; blast radius; accountability; data export.. which means either they don't have the power to make such commitments (wouldn't be the case pre-acquisition), or don't want to make them. Another negative signal.
Their envoy is out of the loop so when Hack Club tries to respond they are at best rejected as some spurned rouge customer, and at worst completely ignored as they fail to reach anyone who has the power to properly look into it. So they have to go nuclear and make things public just to get the attention of a billion dollar corporation.
The fix, if any of this speculation is accurate, is indeed cultural. One counter to the current culture of tech trying to lay off as much as they can and letting Customer Service rot on the wayside. These PR crises were long determined as an "acceptable risk" of such cuts.
I don't think our engineer quoting Rob upstream has anything directly to do with this (maybe Rob does, but that's too speculative even for this post), but I do think we need to bring some shame back to corporate America. This is indeed endemic at multiple companies, not just Slack. I hear this is one of many reasons companies prefer to deal with Chinese companies; these kinds of CS slip ups just doesn't happen in their culture as regularly as the US.
Fixing the immediate problem is only step one. It's reasonable to ask for accountability and that they tell us about what they're changing going forward.