well then the question would be, why shouldn’t it be public knowledge?
If you publicly sack someone, make the announcement publicly as breaking news it’s not unreasonable to think that people should be told why.
And the reality is that if it isn’t made public knowledge people will make their own deductions, which may not be anywhere near the truth but which may still have the ability to harm someone’s reputation.
Clearly whatever he was sacked for was serious, but if someone is sacked for e.g. addiction issues, people have a far different view of that than when someone is sacked for downloading disturbing images such as in Hugh Edwards’ case.