Why did he not say “Yes Sir” and left when given that option?”
Because it was wrong.
Because it was illegal.
Because if you don’t stand up for your rights, you will end up losing them.
Because if he did, he would end up having to do it again and again or stop carrying.
Because letting them do it only makes it worse for the next person they harass.
Because if it continues, someone is going to get killed.
There are two types of people; those who defend their rights, and those who enjoy the freedom that results from those sacrifices. Those who view such encounters pointless, even foolhardy (the freeriders) will never understand what motivates the defenders.