Its a free way to test he knows how to use SSH w/o a SSH server to talk to on the other end.

One can simply start an openssh-server on localhost with some unused port for testing. There is no need for the internet, other computers or let alone other computers from somebody else over the internet for that.

Yeah I'm sure they are running linux. Actually just have them build openssh from source first. Much easier then signing up for GitHub and following their guide to do a test push for a litmus test.

The person in question is a project manager and may be using something other than linux or mac.

I use Ubuntu Gnome. The company I work for does not use any OS other than Linux.