Yes, that was for emissions control. Sometimes it got too hot under the hood (in the engine compartment). So they brought cooler air in from outside. It still kept the air at a constant temp as the heated air intake functioned at the same time. The idea was to keep the air temp constant via a balance of warm and cold air rather than to get the coldest possible air. That's what the big diaphragm on the intake snorkel is for, it controls the flap that regulates the hot and cold sides.