I was on an online peer review group for unrepresented writers (and for people directing their own films). Occasionally a reviewer who was also an actor would object when a script told the actor how to perform a scene.

But an actor is unlikely to be the gatekeeper for a spec submitted to a prodco. The problem would be if the studio reader thought that "directing from the page" was a mark against the storytelling. However (speaking without real-world experience here), the "pick our spots" advice should take care of that problem. The occasional, well-chosen use of a directorial note shows that the writer knows the difference between a device that serves the story and a device that tells the story. Arndt not only establishes that he knows what he's doing in terms of restraint, he also creates a confident voice for the narration, which promises that the story is likely to be a fulfilling read.