You are just saying what they did with the older carbs before they had electric chokes basically and I can see it makes sense. The choke piston in the housing does not had a perfect seal or rings or an o-ring on it as vacum leaks past the piston and on the older carbs the vacum source was a slot in the choke piston housing that only pulled the piston as far as it could until end of the vacum slot gets uncovered by the piston as thats as far as the piston pulls and then you can bend the linkage to adjust the choke pull-off opening. They always did as I said earlier and used that vacum source which is basically a small controlled vacum leak as it pulled fresh air from the carb air horn through the exh manifold to heat it and into the choke housing to heat the coil. Almost like a PCV system in the fact that it is a small vacum leak (source) they use and just make up for the small amount of extra air in the carb adjustment. Its always been more or less to me a controlled vacum leak used to draw hot air into the choke so I can understand that it can still be a small controlled vacum leak like was used for years and years on the older carbs. It may be the vacum leaking past the choke piston and if it is not there and the choke thermostat is sealed to the housing then it would just build up vacum inside the choke housing. It may just be to vent the vacum leaking past the choke piston to outside and if thats what they did then they made up for the small vacum leak in the carb adjustment as was done for years. I have not heard of any reason for it to be here to cool the electric choke as that would kinda defeat the reason of what the electric choke coil does. At least I have not seen any electric choke coils need to be cooled after they heat up while the eng is running since most have temp controls in them. Ron