I'm unclear why it's important for the actual guy on trial.
According to these latest articles, the German prosecuters have a circumstantial case against Mzoudi as accomplice to murder re: 9/11, but one that isn't complete.
Most observers were ready for an acquittal before this witness's testimony was entered as evidence at the very last moment.
This new testimony tidies up the prosecuter's case in that it represents the combining link in the other seemingly unrelated pieces of evidence the prosecuters had.
Mzoudi was the messenger between the organizers, the middlemen and the perpertrators. Mzoudi knew the codes. Without Zakeri's testimony it would appear Mzoudi knew the other parties, but there was no evidence that he knew them for the specific pupose of planning the 9/11 attacks.
HTH
longjack