The coolant runs though the thottle body for the air control valve. This allows air to enter when the engine is cold. Toyota uses a wax pellet to actuate this valve. When the wax heats up it expands and closes the air bypass for normal idle. It has nothing to do with warming the throttle body, or air entering the engine.
Nope, completely wrong.
There is no "air control valve" on a 1GR-FE engine. Basic idle speed, additional throttle opening when the AC is switched on, increased idle speed when cold, etc. are ALL handled by modulating the servo-motor-driven throttle butterfly, in conjunction with the Throttle Position Sensor. The Idle Air Control Valves used by Toyota for the last 20 years have been electronic, controlled by the ECU, not a wax pellet or bi-metal spring.
The engine coolant through the throttle body is to prevent icing around the throttle butterfly in cold conditions with high humidity. On one side of the throttle butterfly is atmospheric air pressure, on the other side is very low pressure (manifold vacuum). At small throttle openings, as the air passes across the throttle butterfly, the air expands and cools even further. If the intake air is already cold, the air temp max drop below the dewpoint, and moisture may condense just downstream of the butterfly. If the throttle body gets cold enough, the moisture may form frost or even a buildup of ice. Moisture from the crankcase ventilation system, fed into the throttle body via the PCV valve, may also contribute to condensation or icing.
This wasn't usually a problem when intake manifolds were big chunks of cast aluminum, and conducted heat up from the block to the throttle body. The later plastic manifolds (like the 1GR-FE uses) conduct little or no heat to the throttle body, and some form of supplementary heat source is required. In some V6 models, Nissan used an electric heating element just downstream of the butterfly. Toyota uses engine coolant in many models.
Carburetor icing in reciprocating aircraft engines is a serious and potentially fatal problem. In a carburetor, there is substantial additional cooling effect as the fuel is pulled into the carb venturi and changes state from liquid to vapor. All aircraft carbs are equipped with some kind of pilot-controlled anti-icing system to prevent in-flight engine power loss or shutdown due to carb icing.