I don’t necessarily think paying MaidSafe to do an app makes sense at all. Why would they write an app they don’t have control over? Nor do they have the dev resources to divert to that project.
I also think calling him out for his rate is uncalled for. Sure, in the UK, and pretty much every country not the US, devs don’t make as much. I’m not saying he is from the US, as I have no idea, but $50/hr is a reasonable price for even a minimally experienced dev here. There are salaried devs with 5 years experience making $100k. Heck, on the West coast, that’s right out of college money. Any contractor in the US makes ~20% more than salaried employees to account for an additional tax burden and insurance, so $50/hr is really a bargain price for a dev in the US.
I have no intention of hiring someone to do coding, since I could do it myself if I really desired to, but if you are hung up on the pay, you can always go on Fiverr, or something, and hire a dev from India for pennies on the dollar. Meanwhile, this guy is here, and seemingly enthusiastic. I don’t like his chances of getting his desired full time gig from this, but if someone wants a project done and has a pile of money to hire a dev, it seems like a reasonable proposal.
It would be probably helpful for the OP to code up a simple chat program, or some other simple task, with a minimal UI, and put the code up under some throwaway GitHub account to at least demonstrate basic competency, though. I understand the desire for privacy, but offering zero proof of ability is a little odd. Seeing as even the most basic tasks showing competency would cost the client $400-500, that’s a decently large ask on faith alone.