By definition, someone who cannot provide enough food for themselves every day is vulnerable.
They are insecure in the daily necessities to sustain life. They are in emotional survival mode.
So you described what they are vulnerable too, and that doesn't include turning to God, just because they are hungry. If anything these people can be angry at God, and would be the toughest to convince, if that's what I was doing, just trying to convince them that God exists.
All people are vulnerable.
Social pressure is being applied to these people to listen to a testimonial.
Possibly, but not if you ask if it's alright to talk about it first. What if I was talking about r/c planes?
He actively tries to create opportunities to share his story. He asks leading questions to try to get people to ask him about his story so he can tell them about god.
Well not exactly. You could also say that God puts me in these situations.
I also create opportunities to talk to people about r/c planes, is that exploitation also? I am not selling them anything.