Anyone who believes this crap has never been in front of a stallion that strongly desires you to be somewhere else.
Not really- the snort means “I feel awesome” and a stallion is trying to convey his status, not his weakness, so he’s going to snort to express how awesome and fit he is. But stallions in a territorial mood don’t just snort, they add a lot of other signals, too. He’s saying “get out of here” by pawing the ground. Done at the same time it means “Get out of here because I am awesome and I am going to bite and kick the s#!t out of you if you don’t.”
People grin because they feel good, but people who grin while cracking their knuckles, puffing their chests out, and putting their feet in a wide stance, etc., are sending a stronger message not unlike the stallion.