When a member finds out you're actively looking for an escaped android her response is just to ask you to stop. No threat or anything. Just a plead to show some humanity.
They could be more powerful in the time since 3, but I doubt they have anything even close to what the institute can muster up.
@cinder: I didn't say they don't care about human life. I said they do care about it. They are against slavery in all forms, and are obviously pretty good people.
I find it hard to believe they are going to go around shooting MIT scientist on site. Victoria from 3 doesn't even threaten you, just appeals to your humanity to let the android live his new life.
I base it off evidence found in game. These aren't soldiers or their movement wouldn't be underground. Liken it to the real Underground Railroad or people helping Jews escape nazi Germany. They weren't killing nazis to accomplish their goal, but using networks of connections. That's kind of what a railroad is...hence the name.