The French citizen has no family or connection to the US.
The French citizen has a master's degree in Business.
Can he search for a job while in the US as a tourist?
Does he need to find a job with a company that will sponsor him while he is in France, and then apply for a H1B visa, or can he apply for an EAD as he is searching for a job in the US?
A tourist can search for a job while in the US. With your master's degree you can have an employer petition on H1B visa for you. It is imperative that you do not overstay your tourist visa.
He cannot apply for EAD without a category for EAD, as EAD has to be related to a submitted application.