When made by an employee clearly stating as such, it can be interpreted (legally) as representative. Exactly why most of us emailing from our company mailboxes have disclaimers. Even then, it's still a grey area as it will depend on wording.
However, in this case, it is clearly made by a member of staff ON THEIR OWN WEBSITE. There is no disputing the forum in which this appears, that it is a member of staff (or someone representing themselves as such) and the tone of the response clearly reflects poorly on the ex-employee. He may well also not be able to access the forum or be aware of such a posting an so defend himself - it's clearly a cheap shot to get on the customers side.
Personally I'd think long and hard before I considered sending such comment in internal email, whether about a colleague, ex-colleague or customer. I most definitely wouldn't put something on a public forum, where it could fairly easily be tracked back to me and/or my company. Even if it is someone impersonating a member of PN staff, PN should have removed the post with an eplanatory note, rather than leave it there in plain sight.
Again, I reiterate, this is highly unprofessional.
plusnet 1MB rural connection.