If it upsets you this much, send him a message voicing your feelings. I'm sure he'd be willing to listen to one of his top patreon donors, which you clearly must be. In fact, you should just go all out and commission the rest of the project, ask him what that would set you back. When you do so, make sure you get a timetable and hold him accountable to it. Get a lawyer involved if need be.
If someone goes to a restaurant, orders a meal, and it takes the staff four hours to bring their food out and when they do it's only a quarter of what they actually ordered, are they not allowed to complain about how utterly shit the restaurant is unless they buy out the business first? Is that
seriously how you think...?
Because that's exactly what's happening here: people are getting a
fraction of what they're told they're paying for,
long after they were told they would get it.
EDIT: Also, it's cute that you think a message would even be read. Dude doesn't even bother paying attention to his own discord server anymore