What photo?  Do you have a link to the photo or the post?

Thanks for providing the image.

Let me start by saying I'm not a lawyer, nor am I trained in legal matters related to forums on the Internet.  Questions about copyrights and related stuff have come up in the past though, so I have read a little bit on the subject to try to get an idea of things.  When a user posts something on a forum (not just slinging.org, but any forum), that person holds the rights to their own words.  This includes pictures, video, etc.  Basically in the event of any legal situation, a user is responsible for what they post and not the forum.  So no, slinging.org cannot grant use permission for any content posted by a member.

Content that already has a copyright is another matter.  It's technically not legal to post copyrighted material on a forum.  Unless of course you're the owner of it.  That obviously does happen though (meaning copyrighted material getting posted).  But I think for the vast majority of situations it's either unknown or ignored by the owner.  As an example, if someone finds an image of a slinger on the Internet and posts it here, it's just for communication/entertainment purposes.  No one is making money from it, or using it for advertising, etc.  I'm not sure where a "fair use policy" might come into play, but maybe I just described it.  Again, grain of salt for all the legal stuff.

All that aside, I ran a Google Image search on the picture.  The earliest result it found is this one from 2013: https://www.jpost.com/magazine/features/hot-off-the-arab-press-329593.  In the linked article, the caption under the image reads photo credit: REUTERS.  I searched for Reuters and here is their website: https://www.reuters.com/.  You could try reaching out to these websites to inquire further about the image.