re: Accepting two jobs, unethical or wrong?

He needs to look carefully at the job requirements for both jobs to make sure he is able to fulfill both simultaneously. Do they require him to be available or on call during specific hours? If both do, then he could be in conflict if both need him at the same time. Do they require him to spend a specified amount of time on certain activities? If so, they probably expect that time to be used exclusively for their activities and not split with someone else's. Can he spend the required time for each separately?

Chances are that both companies expect him to devote a certain amount of time exclusively to them. If he's splitting his attention during that time, he's not living up to the requirements of the job and the companies will not find that acceptable.

Bottom line is the point you already made. If it's truly no problem, then he should be able to tell both companies what he's doing and expect no negative feedback. If he thinks they would react negatively, then they probably expect him to do something he isn't doing.