I'm not sure what was ambiguous about my initial phrasing, but to elaborate for the sake of clarity, I'm talking about the reversal of Chevron doctrine (i.e. the topic of this thread) -- under this doctrine, the federal courts had delegated interpretation of the statutes under which administrative agencies operate to those agencies themselves.

This created a state of affairs in which agencies were indeed making rules that were binding upon the public, and doing so without the courts exercising oversight on their own part to determine whether those rules were consistent with the prevailing statute law.

Now that Chevron doctrine has been reversed, when agencies engage in novel rulemaking that expands the scope of their authority, it will be up to the courts, not the agency itself, to decide whether that expansion of authority is consistent with current prevailing law.

He's probably referring to Administrative Law Justices (ALJs), who are part of the executive, not the judiciary.