... meaning he has admitted his own wrongdoing over some of Autonomy's deals.
I don't think it necessarily means that. Rather it may merely mean he feared - rightly or wrongly - "they were out to get him".
The witness looks bad. But that may just mean the lawyer is doing his job: Qu'on me donne six lignes écrites de la main du plus honnête homme, j'y trouverai de quoi le faire pendre.
Yes of course I believe almost certainly the case is dodgy and the witness compromised by the US trial. But not so much on the strength of today's report.