Why? And what the hell has it got to do with political correctness? A person has committed a serious infraction while employed. His former employer is washing their hands of him, and the things he has done are tainted. The nature of what he did necessitates a short statement. But they don't, and shouldn't have to, go into the exact details just to satisfy the curiosity of unconnected people, because really, that's what you're asking for. If it were to go through public court, then it would be on record, but it hasn't, and no employer with an iota of sense/HR department ever willingly releases detailed private internal information on an investigation. Sure, it might be great big conspiracy, but more likely is that he's a huge arsehole who abused his position and is now on the receiving end of utterly predictable consequences.

Edited in response to comment below, exact same point stands.