Oh Greg, are you stressed?
Indeed a very immature email from a Manager struggling to maintain control (and bonus?). Or did Greg have to pick up a headset and do some real work to help out?
I hope any staff member offended by his email contacts HR to express their displeasure.
Perhaps, Greg, you were short staffed because:
a) People do get sick, and
b) Nobody else wanted to work overtime? (Keep in mind Greg that you cant force someone to work overtime if they don't want to and you can't prevent people getting sick).
Finally, Greg, if you hired adequate staff levels maybe this tragic shortage of Controllers would not have occurred? Perhaps it is 'you who is in the wrong job'?