The bigger question is is he wrong? We can jump straight to Marx said it so it must be wrong (adjacent to the "Nazis believed in gravity so I can fly!" line of reasoning), however, what he said is really not that controversial. His overall point was two things, first, that workers have different interests than their employers. It is in the workers' interests to be paid more, it is in the employer's interests to pay their workers less. It is in the workers' interest to work fewer hours for the same pay, it is in the employer's to work more for the same pay. It is in the workers' interests to be given more paid vacation time, it is in the employer's interests to give less vacation time. It is in the workers' interests to pay a smaller share of the tax burden, it is in the employer's interest to pay a smaller share of the tax burden relative to workers. Class warfare, dramatic a term as it is, is merely the acknowledgement that the two groups in the labor dynamic have some mutually exclusive interests and so there must be give and take between them.
His second point, which your thread has demonstrated nicely by the way, thanks for that, is that even mentioning this dynamic instantly starts the faux outrage machine and degenerates the conversation into nonsense and partisan bickering over what should be a noncontroversial point.
Can we admit the interests of workers are not always the same as those of their employers? Can you point to anything in his article which is actually wrong? In all honestly, for all the hubbub I was hoping for a more interesting and controversial article.