By now anybody who's interested is likely to have made up their minds about the Johann Hari business: about how serious or otherwise a misdemeanour against jounalistic ethics his way of writing up interviews has been; and about whether an apology from him should suffice. I make no attempt here to offer judgement on the first of those two issues. But on the second I would say that an apology from Johann would suffice if it were clear, non-evasive and acknowledged in full what was wrong about his interviewing 'technique'.
I don't think his apology meets this standard. Johann says that the accusation of plagiarism against him is 'totally false', and in support of the claim he writes that:
Plagiarism is presenting somebody else's intellectual work as your own - whereas I have always accurately attributed the ideas of (say) Gideon Levy to Gideon Levy.
But this is subtly - and self-servingly - to narrow the meaning of the word 'plagiarism'. By saying, first, 'intellectual work' and then segueing from that into 'the ideas of' Gideon Levy, Johann omits forms of plagiarism that involve using the work of others without making due acknowledgement. This is certainly a meaning of plagiarism. If I report as having happened to me an encounter on a New York street with Wayne Gretzky, using the exact words of someone who really did meet Wayne Gretzky on a New York street, and I pretend it happened to me, then that is plagiarism. I'm not stealing anyone's 'ideas', in the way that this is usually meant; I'm not passing off as my own an argument, or conceptual proposal, or novel thesis, of some writer or thinker. But I am improperly drawing on the work of others. The New Shorter Oxford gives for 'plagiarism': 'The action or fact of plagiarizing a work, idea, author, etc.; literary theft...'; and for plagiarize:
Take and use as one's own (the thoughts, writings, inventions, etc., of another person); copy (literary work, ideas, etc.) improperly or without acknowledgement...
This covers what Johann was doing. The fact that he didn't try to pass off the ideas of his interviewees as his own doesn't eliminate the plagiarism involved in passing off something of the work of other people than his interviewees as his own.
If you were accused of a theft at the Oversight Hotel, it wouldn't establish that you were innocent of the charge merely to show that you hadn't stolen anything belonging to the hotel itself.
Whether for these reasons or not, an online poll at the Guardian suggests that by a ratio of 3 to 1 people aren't persuaded by Johann Hari's apology.