I guess we will have to disagree on the snort, what I've seen, and I guarantee I have seen and heard at least as many as you have, tells me a different story. It's clearly used to clear their noses, if you watch them do it, they always sniff the air right after a session.
I've been talking to deer for 40 years... there are dozens of vocalizations that they make at various times, and at different times of the year. As for deer "blowing," I disagree with you, they are not "clearing their noses," they are most definitely issuing a warning call to other deer.
Ha, when that one first appeared, it made the TV news.This.
Had a mulie doe walk right up to us within 5 ft on a pipeline to check us out then walked around in front of us for over an hour as we were not a perceived threat.Funny how they know your intentions.