You have to assume he was a) aware of the organisational policy and advice about online useage and how it can be used against you and do damage to the brand (he was working in branding and pr) b) Ignored it all anyway, cos he thought it didn't matter nor apply to him for whatever reason.
Giving the benefit of the doubt its naive and stupid. But the tone smacks of arrogance, entitlement and that it was something that was totally ok.
And I stress again, this is someone hired on the premise that they were supposed to understand public image and how that is maintained and promoted. This isn't someone who has no awareness of this. It was their fucking job to understand it.
He was a terrible hire. He's been pulled up on it previously.
No one followed it up.
Therefore you CAN NOT say it is anything BUT institutional and throughout the organisation as it series of problematic issues that more than one person were in some way involved in.
He might be the focus but the more you look at it, the more you can't say that other people WEREN'T aware of it. And even if they weren't thats an institutional failure in its own right, because they bloody well should have been.