This is at least as a US Company, I don't know about how UK or Australian businesses might differ.
I don't disagree about using good people wherever they are, just I am cautious on blanket statements anymore cause so many things can bite you and the rules aren't always so straight forward when you cross international boundaries. So the key is just to get some legal/tax advice so you know the best way forward. It is definitely very doable and doesn't have to cost a fortune if like you said it is a true contractor and they do not hold US citizenship or travel to the US for business and they are working from a Country the US has a treaty with. It can get more complicated if those aren't the cases.
edit to add this: Also if you do business in their home Country, e.g. sell a service even over the Internet that can change the tax situation too in their home Country for you (based on their Country's laws). Another thing to always consider, doesn't rule anyone out, just something to ask about.
Be kind. Don't be snarky. Comments should get more thoughtful and substantive, not less, as a topic gets more divisive.
When disagreeing, please reply to the argument instead of calling names. "That is idiotic; 1 + 1 is 2, not 3" can be shortened to "1 + 1 is 2, not 3."
It's quite hard if you want him to be an employee though.