So refund in full and do the rest? That's what happened anyway, isn't it (the refund)?
The point was there were options, but the creator didn't seek them. So many people wanted that app to continue living - I find it impossible to believe the creator couldn't get an extra $1 a month (or even a lot more!) from those users.
How many apps can boast they have 50,000 paying customers? People need to appreciate just how difficult of an accomplishment that already is. The paying users loved the app, and would have paid more to continue using it - especially in light of the available information at the time.
A massive proportion of us didn't request a refund. I don't know the percentage, but I would not be surprised is most users didn't ask for a refund of $10.
You're probably right that there was some way for Christian to navigate this and keep Apollo up. But I also don't blame him one bit for throwing his hands up after how that whole API debacle went down. Must've been pretty stressful.
I believe Apollo was open sourced after it's demise. You could run it yourself but then you'd have to contend with the intentionally difficulty of installing software on the iphone.
I don't think the app store provides a mechanism to do this.