It's your problem - to get a B1/B2 visa he must have a US citizen sponsor
the application. It isn't hard, but definitely easier if you and he can visit a US Embassy together. I got one for a crew member
heading to Norfolk in 24 hours. If you have to ship documents back and forth with notarized signatures it will take longer of course.
Shouldn't be a problem for a French citizen; I have no knowledge of our treatment of applications from Argentinians.
There will be a minor background check. Conviction of any transgression that would be a felony in the US is a problem. A pattern of more minor convictions is also a problem.