Don't forget that the Northstar doesn't use GM's "Thermactor" system (heated intake air). In pre-2000 engines the throttlebody itself is heated by engine coolant passages, so the bore perimeter is always at engine running temperature. Later models attach the throttlebody to the coolant crossover, so there's heating there, too, but not as much as earlier. Fuel injector timing and pulse length take care of the older heated intake air warmup cycle.
The directly heated throttlebody was primarily designed to combat butterfly area bore icing: as air rushes past a slight (part-throttle) butterfly opening it loses pressure rapidly just downstream, causing vaporization and supercooling of the moisture content due to relative humidity, thus theoretically causing ice buildup under certain temperature and humidity conditions. It was later determined that this was not so much a problem as originally thought, and the later indirectly heated arrangement has proved satisfactory. The OBD-II comforming more sophisticated PCM fuel/air programs also helped.
If you think the throttlebody casting on a pre- or post-2000 Northstar is nice and cool from your so-called CAI pipe, come in from an in-town rush hour commute, shut down, pop the hood, and wrap your hand around the TB. You'll very quickly wish you hadn't.