Two lines of thought from me:

1. Donations don't work. I can assure you.
2. What if Stellarium Mobile is kind of a wrapper around Stellarium? Or an improved repackaging (optimiized configs etc.)? The source for Stellarium is (was?) GPL and is also available as such, but if the original author "rewrote" the critical parts or optimized parts for the Mobile version that were originally his works anyway, it's not so easy anymore. Remember that the author of Stellarium Mobile is the main author of Stellarium (by a large amount)

And yes, I'm gonna buy it right now. Fantastic app.