This is also the core conceit of Slow Horses, the Gary Oldman AppleTV show. An office filled with MI5 officers who screwed up and so can’t be trusted with anything important.
No, he was sent to Slough house over his reaction to that mistake. He disobeyed orders, caused panic at an airport, and assaulted a civilian. Now, that would have been fine if he was trying to save lives, but the whole thing was just a training exercise! He deliberately put people in danger just to massage his own ego; he absolutely deserved to be "exiled".