I agree with you that expecting to finish a whole, working theme with Jack's current state of those skills can be frustrating. I just wanted to find out what he really needed, in case it was one of these few scenaries in which he doesn't need to build a whole, working theme, in which case i thought I could give him some guidance.
Also, I wanted more information on his coding skills: he can't write PHP, but seemingly he can read it. In some cases it may be enough to understand what a line of code does, and where to copypaste it, even if he doesn't know what a method or OOP are, specially if, as he confirms, is being assisted by a mentor. If Jack is trying to make a new theme that looks pretty, like the commercial ones, or even a fully functional theme, he will need to know PHP and browser coding, no matter what. But I think that if he only needs a naked base theme, like the bootstrap one bundled with moodle, he can manage something very similar using the approach I suggested.
I don't want to make it look like an easy task, but I think my suggestion is backed up by Mary Evans' experience she explained a few posts ago.