Because he was just trying to see what was going on. He sees the military cargo shyt crashed or w/e and sees something sketchy. On top of that he drunk and probably ready for some shyt to go down anyway because of his frustration with the Ghorman resistance not doing anything. He was one of the dudes speaking at the rebellion meeting. It couldve been as simple as him wanting to go fukk up the cargo vehicle, to feel like he doing something to fight the empire. Then you got this random walking up to you saying "go away, this isnt for you". He probably felt like "nikka, who the fukk you talking too?

" and dude pulls a gun because he too inexperienced to defuse the situation w/o violence.The young dude shouldve known that was a person in the rebellion meetings, he couldve defused it on some "Hey, it's me Youngguy from the rebillion meeting, we up to some shyt

, chill out so we dont get caught" and dude wouldve listened.