It sounds interesting.
I will not vote, as this is not my genre: not intended for me.
If it was my genre (Mother/Son Incest), I would want:
John:
1) Mother non-NTR.
2) For others, it's ogre.
I would want John to be a champion: not a push-over Shota perv manlet.
And I would want my spine to eventually get un-fucked.
Regarding NTR allusions:
NTR path: no closure unless climax.
Non-NTR path: closure.
Providing closure by casting allusions away requires an effort to convince the player through historic knowledge of LIs, through the LIs themselves, or through the world somehow.
If MC is going to get neglected and laughed at by NTR world all day, the tease will clearly be tuned to the NTR crowd solely.
Of the set of people who don't like NTR, only a portion relative to the extent to which the tease bothers them will bleed from the potential demographic.
Oh!
And development time (causing cliffhangers) can be a part of the problem.
If I follow a non-NTR route, it would be much as you describe. I am personally not a fan of young or boyish protagonists. John would be less a shota perv, and more a guy who let his dreams go for mediocrity, then was forced to hit rock bottom, and with renewed passion climbs back up far higher.
In short, a kind of learning to be alpha character type. And yes, this path would include completion of treatments and being able to walk again.
Development time and cliffhangers do concern me. As a player, there it is very frustrating to have plotlines linger for years due to the dev trying to do a dozen plots at once. My general thought as of now is to tackle one route at a time and thus provide the quickest dev time to a completed story. Then I can turn to other routes or add on to existing routes.