An Evil Plot
The OP’s workplace divided the employees into two separate groups to take courses against sexual harassment at the office. That actually sounds like a good thing, seeing as how harassment is still prevalent in today’s culture. However, it was the second group—the ones that attended the training on Friday—that was the real problem.
The second group was fired on the spot since the company considered them to be the worst offenders. Now, there’s no telling whether that was true or not since they hadn’t even watched any training videos before being laid off. Why couldn’t the company just fire them from the start?