Fair trial
That will be the day, OSA, Terrorism laws all weasel worded to screw over the accused.
So, you could be a whistle blower revealing "evil" govt behaviour, but if some of that "evil" is OSA covered then guilty even if you are trying to expose something nasty your govt did.
Caveat - I have no clue what this person is alleged to have done / accused of, just know the wording of too much UK law is really bad (as I think El Reg (kudos) attempted to highlight with some of the OSA related snippets they put on the page)