If it was what happened, I would definitely agree with you. Refugees camp are not for tour sightings. But the one who captioned the picture isn’t from the charity, he’s the guy from the restaurant they had a meal in. He doesn’t necessarily know everything about what they where doing there and why.
Knowing Gillian and her involvement with many charities, she’s not the kind of person who just walks by a refugee camp to see how they’re settled in and approves, then go have a meal in a fancy place. If she’s involved with a charity organization, it means she helps, in a way or another.
So as long as she doesn’t tweet anything, if the charity itself don’t say a word, we can’t judge what she was doing there.