Not sure what to tell you, but the code is available on their GitHub organization. Both Nemo Mobile and AsteroidOS use it and have working window management and such because of it.
Btw I just read https://catcrafts.net/posts/fairphone-6-postmarketos-working-main-camera and the section "Meeting the lead pmos dev" jumped out at me. Ik ben dezelfde van Tweakers die je daar noemt ;) But I'm not the lead dev. In fact, there is no lead dev. There is the core team of which I'm part, but calling me a lead is misleading.
Also you said "can be disproved with a 10s search" but I searched for at least a minute and didn't see it. Sure I could've tried harder but then again, this was just something said under a Tweakers article, I won't dedicate to much time to it ;). I understand that you didn't like that I thought you weren't upstreaming things, but now you're calling me out as if I did something wrong while I honestly tried but just didn't manage to find anything. I rather not have us calling each other something we're not and I most definitely did my best not to.