As for the ongoing discussion, here's my take:
1- The ONLY case you can make in favor of Stephany being an adult is: as a fictional character, she is whatever the author says she is. If he says she's a mentally challenged, underdeveloped, short girl, than thats what she is. Any other argument is mental gymnastics. What you make of her in your own head canon is up to you, but lets not pretend we don't know the intent here.
2- "Patreon rules are stupid and unfair".
If a creator is unhappy with the Patreon rules, he's free to use other platforms. As long as he uses Patreon, he's supposed to abide by their rules. A ban here would not be unjustified. If Patreon decided they had enough of adult game creators using low-effort workarounds, then they are in their right to purge everyone.
3- We don't even know if this matters. Its not like the development was cruising before Patreon stepped in. Maybe this is what kills it, or maybe the game was already dead. Either way, it's the dev's job to communicate what's going on to his supporters on discord or whatever. So ultimately, even if Xenorav is struggling with the Patreon situation, and thats what's holding the game back, he's not doing himself any favors with the radio silence.