You're trying to work with that company, help them to use your platform. There might already be some personal attachment here if you really believe in the platform you created and take personal pride in every OEM hopping on board, but even if he just believes in the "greater good" of having this unified experience on Linux I can see how he wants this to happen.
Then there is Apparently some capable person at system76 who reverse engineered the proprietary updater they had to use before, and this is where things start going wrong. This is the part I have experienced personally on both sides. The system76 guy gets a great ego trip out of his achievements, somehow management/marketing hears about it and together they brainstorm how they can build their own independent update infrastructure. Marketing sees their unique selling point, dev sees exciting new things to create, feels like internet super hero, tells lvfs how shitty their whole approach to this is since super-dev has so much more insight into how this should be done properly.
However, two inputs to this. One is that it appears that S76 had to work to do in order to become compatible with LVFS, and ended up just extending this to the point where they had an updater. Two, I can't possibly imagine anyone considering a custom firmware updater a selling point, especially not at the cost of not getting the free labor of having someone else maintain both tools and infrastructure.
I kinda suspect we were dealing with a "Hmm, we could just sprinkle a bit of UI on this and then move on to other tasks", knowing that it was suboptimal, but not finding the issue important for the time schedule.
When I cut corners as a programmer at work, it's usually due to time constraints, priorities or annoying customers, and leaves a bad taste in the mouth of developers and managers alike...
I agree that sharing process is important, and your MongoDB example is a good one (not that I am short on reason to not use MongoDB).
However, I don't find the post to describe System76 processes beyond "there was email communication", and that progress towards a goal aligning with the author's preferences was suspended. The only thing I can conclude from it is that the author is in disagreement with System76.
From the format of the post, I would quite frankly be biased towards assuming that the problem lies with the post author. This assumption is of course not based on tangible evidence, which would require access to the email exchange to obtain.