Your argumentation is spotless; I understand what you're saying and there's nothing to argue about there.
It's just opinion vs opinion; preference vs preference.
I will not accept a WIP feature into OXCE main branch, but I can offer help in some ways.
We have similar examples from the past (and even the present):
1. example from the past: Soldier Diaries and Commendations (by Shoes):
https://openxcom.org/forum/index.php/topic,1718.0.html -- it took more than two years before this feature was merged into OXC; in the meantime Shoes worked on his fork, provided test builds, the community tested, gave feedback, even created mods for it -- but the merge happened only after the feature was well known and well accepted by the community
2. example from the present: In-game Map Editor (by ohartenstein23):
https://openxcom.org/forum/index.php/topic,8711.0.html -- ohartenstein23 donated tons of features, which were already merged into OXCE, but even he is not immune against the "no WIP features" rule; he's been working on the map editor for well over 6 months if I'm not mistaken, and the feature also got significant popularity... the work has stopped however, the feature is still WIP and I don't know what will happen to it in the future... but I know that it is a good thing that it didn't make it into OXCE in such unfinished state
Hopefully this illustrates that I'm not treating you worse than anybody else before you.
(PS: there's of course more than just 2 examples, in case you're wondering: the zip loader, android port, sdl2 upgrade, mod.io integration, etc. etc.)
As for the help I can offer:
a/ if you want bigger visibility of your feature on the forum, I can make your main thread "sticky"
b/ if you want bigger visibility of your code on github, I can create a separate feature branch for you, where you can make PRs with WIP code too
c/ if you want help with builds, I can create builds for you from the feature branch in b/ -- alternatively, you can ask Stoddard (the maintainer of our build farm) to create a build farm also for your fork
d/ if you want bigger visibility of your test builds, I can offer you a spot in my main download thread, right next to the official OXCE downloads
That's already more than what I offered to anyone else so far... however, the community support, community testing, feedback, approval and blessing is something only you alone can do.
And if your feature gets popular enough (and finished), and I'm still around by then, I will consider merging it.