Why is there no dialogue option right off the bat that says something to the effect of, "I can see your concern and feel for you and the tribes. But, running from the White Legs now won't save you later. They'll keep chasing you. And if not them, it'll be someone else. If Zion is your home, and you want it to remain so. Then you need to make a stand and fight for it. If not, then you'll never stop running."
Again, I don't remember there being an actual dialogue option but I just met with him and wanted to just tell him flat out to stop being a [censored] and wipe the White Legs out.
I sided with Graham last time I played this DLC (which was about 2 years ago) and I'm planning on doing the same this time. I just don't feel right helping them evacuate when the Sorrows and Dead Horses have been in the valley for a long time.