I don't see the law as covering new ground, but restating the common division of labor in a curmudgeonly and humorous way. Doing so gets people to pay attention, and buy some books. That's all worthwhile, but not new. Here's a few restatements of the law, to illustrate:

• There are those that manage technical systems, and those that manage people systems. There are few who do both at the same time. (And it often works badly when they do.)
• Technical staff should guide the technology towards the goals of the section and the goals of the company. Management staff should listen to and trust the technical staff, not second guess it.
• Management identifies the technical challenges worth meeting. Technical staff meet those challenges.

These less cynical statements are also less likely to get passed around, and thus less likely to have any effect.

Similary, "the correct advice given is the advice that is desired", is another way of saying "solve the non-technical problem that management needs solved". Both are good advice, in that they shift attention from whether the problem is the right problem or the best problem, and point attention back to the job of solving the problem. Management may be brilliant, or borderline incompetent, but there is not a whole lot one can do about that from the technical side.