I know this has already been said multiple times, but here are my 2 cents.
1) Doing multiple paths for your first game is going to be a disappointment for pretty much everyone. The progress will be slow, and a side will feel like they're not getting their fair share of content. Some people will hate the game because one of the sides exists while they are a fan of the other. This is going to be hella amplified because of my second point.
2)The setup is pretty focused on being an ntr story, the protagonist has quadriplegia, and he won't be getting much action in any shape, way, or form for most of the story because of his condition barring it from happening. The non-ntr side will be about building up to becoming normal again, and once you finally get the taste of victory (not being a cripple), the game will be on the final chapter, and you don't get to savor any of it. The ntr path will be the opposite of this, allowing for any fetishes or scenes to take play from the beginning.
having the non-ntr path just be boring (cripple friendly) sex and some shoe-horned romance won't avail you anything, no matter how you spin it, the story is set up to favor the ntr-side, and you will get flamed for this.
3)The non-ntr path as you said is removing competition, regaining control of your family, and regaining the control of your body. do you know what this is? it's not a vanilla/harem path, it's a preventing ntr path. No one is going to play a game to prevent a fetish, people play games for their fetishes.
4)The ntr-tag will drive away a huge chunk of people simply by existing, optional or not. A huge chunk of the people who saw that it's optional will be driven away because of the synopsis/theme of the story, it's an utter underdog scenario.
You are not going to cater to or gain any support from this side.
Overall, the game is an NTR story from the start, don't waste your time forcing a different route simply so it can exist.