To build trust and adhere to law, corporations will usually have processes and regulations in place that determine which employees can access and modify what. That is why spez modifying user comments is such a big deal. It showed that Reddit is not to be trusted. Nevertheless, for corporations that value customers trust, any employee who does not adhere to these procedures risks their employment.
On smallish fediverse instances none of these procedures need to be in place, the admin is bound only by his own moral code.