Given the example from the comic the email he sent would be sufficient proof.
“I was sick the day of training and HR never rescheduled. Why, did I do something wrong?”
Negligence of that order would surely be prosecuted.
Edit: a claim of duress would probably work though.
… Never worked for for a company that did training in such a way. The training is mandatory because they are usually required to show these items for their insurances. Usually you have weeks if not months notice and have to renew it annually or some dumb crap. They are also usually done on their training websites. 3 companies I have worked for just deactivate your AD account if you don’t get it done in a timely manner. Companies who can lose millions or lose actual information that will hurt other companies and get sued do not mess around with their responsibility on such.
Mom and pop shop… it wouldn’t matter much in the first place. Restore the data, reset passwords and call it a day. Medical, military, or such… No fun.