I add those to the metering valve covers on model airplane engines all the time. I put a piece of Tygon on the fitting and run the tubing back in the fuselage to get to more stable air pressure. Sometimes I just solder a piece of brass tubing in the existing hole to connect the extended vent line to.
With this chainsaw . . . .
The area between the cover and the diaphragm gets stuffed with sawdust eventually. The vent hole just breathes back and forth small amounts. I see the elbow as extending the breathing path to where the sawdust will drop out before it gets to the diaphragm?