You can't seriously argue that Walter Williams has a job because he is tenured, however much you might disagree with him.
I'm saying he is probably one of the few who don't have to worry too much about losing his job. He doesn't have some rapacious CEO breathing down his neck to increase profits in his division by 25% a year or face the ax. He isn't some cubicled IT worker being forced to train his replacement in Bangalore or risk losing his severance package. Not having to worry tends to color one's view of the issue.
It's the old adage, nothing is impossible for the man who doesn't have to do it himself. When you can look forward to working in your chosen profession until you retire (i.e., "guaranteed a job", as some here like to rant), it's easy to tell others to adapt or screw 'em, or quit whining and start a business, or get retraining in your late 50s, or whatever.