> The way the EO is written sounds "fine" to my high school civics ears: there's three branches of government, one is the executive branch, and ostensibly the president is the head of that branch.

Then maybe you need to get an understanding of human organizations in general and the US government in particular that goes beyond your high school civics days.

The president has no power or authority to interpret the law, not beyond the implicit power of every citizen to interpret the law for themsleves. The president has the power and authority to execute the law as written, mostly by appointing other people to do so in specific areas. The power to choose those specific people is already huge, directing their every move is neither needed nor desirable.

There are literally tens of thousands of laws, if not hundreds of thousands (when including regulations and binding court precedents) that need to be followed by the federal government. The president simply can't be an authority on all of them, it's not even remotely close to humanly possible.

Not to mention, very tight, military-style control is a a horrible feature. The President may get to command the army, but they are not commander-in-chief of the executive branch, civilian agencies don't and mustn't work that way. Government employees must uphold the law, and fulfill the role of their position. If they're not following the law, they should be fired, and a court may get involved to reach this conclusion. The president doesn't get to dictate what the law is and fire government employees who are upholding the law instead of the president's interpretation of the law.