Could someone explain to me why would anyone use GitHub on their phones rather than on a desktop computer? I can't seem to come up with a situation in which I'd reasonably need to interrupt anything I'm doing in order to check GitHub on my phone.
10 hours a week is very much a second job though. It doesn't really matter when they are, that's a very large commitment over the course of 1-3 months. I'm not sure I know anyone who would be keen to do this.
That's fair – the process has since been revised, and on https://automattic.com/work-with-us/how-we-hire-developers/ we now say "This work is paid, part-time, and designed to last between two and eight weeks, for a total of around 40 hours of work".
It's still a commitment to be sure, but we try really hard to make it as accessible as we can.