the only legal way to broadcast on shortwave radio?
We need to talk about alternatives!
If you're looking into shortwave because he wants to cover a large geographical area, then simple things like web radio could very easily be the solution – at least if the audience has internet access.
Considering current price-per-kB in the US for prepaid cards, you'll get pretty far even with the smallest packages!
Let's run a few numbers, here:
First takeaway: the bitrate you'll need for pretty epic sound quality using a "every mobile phone and PC has that installed already" codec easily fits through somewhat decent 2G cellphone data. Cell phone coverage in the US isn't all that bad – you can probably reach of your audience that way!
As soon as you go for shortwave-comparable qualities, things get really easy to transport across the internet. For reference, I've added the last column, which shows you how much internet transfer volume you'd have to have to listen to eight hours of your station every day of a month. It's rather unlikely that, as a hobby, you'll even be transmitting 8 hrs/day of useful programming, but if you did, that's how much monthly volume you'd want your audience to spend on you :) Corollary: if you've got but a dozen to a hundred occasional listeners, you could even completely save on RF equipment and possibly necessary licenses, and invest that in data SIM cards that you hand out to your listeners so that they can listen to you over the internet, for a pretty long time, depending on how much power you thought to push out of your antenna.