No.
That's now how Patreon works. The whole idea is it comes from the original idea of "Patrons", as in art patrons. The Nobility or Mechant Class would often pledge money for artistic or scientific works on an ongoing basis, and pull funding if they didn't like the progress or were no longer pleased with the subject. With Patreon, you pledge money monthly and you can pull your monthly pledge when you feel like you aren't getting what you're paying for anymore.
So what the author did is they were transparent, and said "Hey, I'm going to stop working on this because of recent events". In my opinion, this is fairly okay as far as closing down development. People have notice, and they can cancel their ongoing monthly pledges if they wish. But at no point (to the best of my knowledge) was a full complete game guaranteed in exchange for pledges. At best, if the game launched on steam, they likely would have given out full game keys to those who pledges a number of months. To me, this is fine.
Now, let's say the Dev strung everyone along for like 8 or 9 months, or a year, or two, and didn't deliver any promised updates or game or whatever. Well, that's pretty shitty. Still though, if they aren't delivering what you want, you could have pulled your pledges, but when the Dev is actively decieving you it becomes more of a moral problem.
If you stick around here long enough, you'll see plenty of Patreon/Subscribestar/etc. drama over devs just milking their patrons/subscribers without delivering and then abandoning their game with no notice.
Yes, that is true. But being denied the use of Steam is a huge loss in potential revenue. It's harder to argue whether a game will make more money on Patreon or Steam (really popular ones will make a lot more money on steam, while most games if they maintain their patron base they'll make more money on Patreon over the long term), but most publish on both if they can and being on both Patreon AND Steam means you make a lot more money than just being on Patreon. Given the very game-y nature of their game (as opposed to just another VN), they were likely counting on that Steam revenue, since it exposes their game to a whole new audience that they wouldn't have found on F95zone or Patreon or social media alone.
Yeah I'm disappointed too; everyone should be disappointed. However, the dev did the cost benefit analysis after the market changed, and decided that a non-compliant game is no longer worth their time. I'm not going to be too mad at them. They announced it fairly quickly and were transparent about it.