I reread the article again. I did see anything mentioned about employees working 2nd jobs on company time, nor was it among the reasons they were fired.

I agree with OP’s comments but the article, not so much. Like OP the Gen Xers I know that are close to retirement with their financial ducks in a row do not prefer to be in the office. Being irreplaceable means you have the leverage to successfully negotiate a WFH arrangement.