Personally identifiable information (PII) does not belong on StackExchange with the obvious exception of whatever information individual users volunteer to share about themselves.
Whenever you see specific people being identified:
- edit the PII out of the post
- leave a comment explaining why so the OP knows why it's gone and that they shouldn't edit it back in
- flag the post for moderator attention
I would always recommend flagging this just so the mod team can take a look, redact PII out of the revision history if needed, and potentially keep an eye on the question in case the OP is on a quest for revenge rather than advice.
Note that this also applies to companies or organisations being "named and shamed".
For the record: the three other answers posted here before mine are all sound advice. This is mostly to confirm it from the mod angle.
I am leaning towards sending the URL to the people involved so they can defend themselves.
I can argue this both ways but in the end what people do outside the network with the information they find here is always up to them. (What the professional course of action is in this situation would actually make for a good question on Main.)