The opening paragraph is an apology. Other parts of the post undo any goodwill that might have been garnered from the apology itself.
One example:
> There is a pattern that needs to be resolved. Projects might not fully understand what joining the .NET Foundation means. We share a checklist with project maintainers on project changes they accept as part of becoming part of the .NET Foundation. That’s obviously not sufficient. We will post a new document that describes what you can expect when your project joins the .NET Foundation...
To me, this says "sooo, even though I screwed up, I'm technically allowed to do what I did and you probably should have already expected that based on the agreement you signed, but we'll make our materials even clearer so you don't make that mistake again".
It turns the problem back around on the community. I don't necessarily think there's anything wrong with the rest of the post after the apology...if it was posted separately. When included in the same post, it's hard not to take it as "sorry, but I still wasn't technically wrong".
I do think the whole culture around public apologies and the hair-splitting and analysis that comes after is concerning and often unhelpful. But I think the backlash here is understandable.