I think what you (and others) seem to miss is that the systemd people made the "debug" option that we introduced not just do something - but do something useless that actively broke other peoples use of that option.
It doesn't matter who "owns" it, the fact is, they broke it.
Ok, fine. Bugs happen, and that's not what makes people upset.
What makes me (and others) upset is that when the bug is reported, with explanations and a suggestion for how to fix it, Kay just closed the bug-report, claiming it wasn't a bug.
Seriously? You want to debug kernel stuff, using the kernel command line command "debug" that makes the kernel more verbose, and now the systemd people say "sorry, we stole your thing and made it useless, and it's not a bug because you didn't call shot-gun".
Now, if this was an isolated incident, I personally would let it go. There are bad engineers out there, it's not worth worrying about. Ignore them and move on.
But this is not an isolated incident. This is how Kay has treated other bugs in the past. Literally months of stalling, closing bug-reports, and blaming other people and projects for problems that he caused, telling others how they should change their projects because he broke something, and obviously it can't be his fault.
And that is a problem.
I'll openly admit I'm not a systemd fan. I've seen too much brokenness from the developers involved, in this and other projects. I've seen far too much arrogance. I see too much complexity. I'm quite disappointed in both the Debian vote and Ubuntu's decision to go along with it (I was really hoping that Shuttleworth would hold out as loyal opposition). Yes, systemd does provide some useful features, but at an extremely high cost in complexity and unproven changes to a system at the core of every last Linux system. Emphasis on "Linux", as it's also not cross-compatible with other OSes on which many Linux programs will run, and on which some distros (such as Debian) provide builds.