The possibility of a misdiagnosis is very real as the shift from histological to genetic definitions was just firming up at that time.
It reads to me like he screened for the -L trial thinking he had true GBM. Then found out later it was IDH-mutant and with the full resection he was doing quite well so dropped out.
Unless there is more information I fail to see how that implies anything wrongful on NWBO's (or Ashkan's ) side Maybe he really was overtreated with Tez (being IDH-M and unmeth). But that would have been the same regardless of any NWBO trial.