I am not familiar with this sense of the term “processing”, so perhaps it's less widely understood than you think. I assumed that in the context it meant the kind of processing the Central Processing Unit and Graphics Processing Unit in my hand computer does, which is pretty broad.

So I thought it was a reasonable criticism of an overly broad or at least very ambiguous assertion, regardless of its motivation. It’s quite common for the best arguments against an argument to come from people who are hostile to it for whatever reason. More carefully defining the scope of things where we would expect COBOL to get top performance marks would make the conversation far more informative and productive.

As for assembly, there is now a broad class of problems for which CPU assembly is far from the fastest solution, because GPUs are faster. Even on the CPU, there is a widespread (but usually false) belief that compilers beat expert assembly programming. So perhaps to you it's a vacuously true statement that adds no useful information, I read it as rebutting a belief many readers may really have (though, unfortunately, only as a bare assertion.)