Your prodigious observations on the 'semi oldish git' may hold just a few drops of water Racedo but I'm not too old to recognise the difference between toxic behaviours by disgruntled employees in the past to those of today who can participate in internet 'bad-mouthing' their employees which is arguably more potent and far reaching than slanderous comments heretofore.
The modus operandi of employees who express dissatisfaction may not be due to an inability to achieve higher earnings or gain an expected higher position but to other genuine factors.
The apology contains everything you'd expect, except Mark (not known) is obviously not endowed with 'deep pockets' and it is that non verbal communication which makes the apology seem manipulated and a bad method of communication.