While Jeff Probst took over the Official CBS Instagram

"CBS Survivor Official Survivor Instagram CBS.com/Survivor"
http://instagram.com/officialsurvivor_cbs/

on Sep 23, 2015 (S31 Premiere date) that doesn't necessarily mean that Jeff was around when those photos were taken.

The photo in question at NuBayon is at:
http://instagram.com/p/7-w6VqOSNp/?taken-by=officialsurvivor_cbs

Here is the full sized image (unfortunately no date/time info in the image)

And here is the caption:

officialsurvivor_cbs"I'm taking over.... This gives you a really good idea of what life at camp is like. They live with so little. You can see how easily a good rain storm could really wreak havoc! Take it in and imagine you’re there. And unlike a challenge, our crew is very small so we don’t disturb them too much. Believe it or not the contestants get so used to the cameras that they forget they are there!"- #JeffProbst

I don't really think Jeff/CBS would use a shot of after Jeff was in NuBayon camp telling them the sad news about Terry's son's health for Jeff's takeover of CBS Instagram.

I agree that this photo was taken around the same time (and probably later) than the full NuBayon camp photo as all the clothes/items are in the same location. To me this looks more like Monica, Jeremy, and Stephen stressing over the vote tonight at Tribal Council than reacting to awful news about Terry's son.

I also do not think that Monica pulling her buff over her top is getting dressed for Tribal Council which would be at night and cold. I would think she would likely wear her Day 1 blue dress:

What Monica is wearing in this photo is what she wore to the Reward and Immunity Challenges.

I think the news about Terry's son probably came after Tribal Council #5 (evening of June 12th, Day 13) during the night and they would be told the next day (June 13, Day 14) Morning (first day of Episode 6).