Hi. I'll start by pointing out a couple of reasons why I don't think this broke the 5 score barrier.
1) The focus seems soft.
Sometimes it can work, but here I think it is too subtly out of focus to look like it is meant to be. It may just have been soft from resizing down to 640x513 without applying unsharp-mask, in which case a quick USM would do the job. Most of the time, DPChallenge voters like a photo to be perfectly crisp, that's just the way it goes.
2) It's a flower shot.
Flower shots are the most hates of cliché's on this website, after kids. Some people see a flower and automatically vote it down without looking for it's qualities. As your connection to the Conflict challenge seems to me to be quite weak with this photo, even with the thorn, I expect many people voted you down for that.
I think this photo could also be improved by cropping in closer on the flower by the thorn, and leaving out all the dark black area around the edge which seems to have no purpose. This would make more yellow so the photo would be more appealing to the general audience.