The fact the guy had a weight belt (and mask/snorkel), which is a very common piece of equipment for free divers, suggests he didn't just dive in for his first time to actually lift an anchor from the surface.
So just to clarify, the number one rule in free diving is "Always have a buddy diver in the water on the surface watching your entire dive." Why? Because a shallow water blackout is very real and common and you need someone in the water to quickly retrieve you and bring you back to the surface. The fact he still had his weight belt on is irrelevant as you're not going to ditch your weights when in an instant you blackout.
I suggest doing some research or watch some video testimonials of what is feels like to black out. Most survivors will tell you they don't even recall it happening and when they come to they have no idea where they even are let alone what just happened. In fact they wake up shocked to be in the water.
The lesson learned here is NEVER free dive without a buddy IN the water watching you with his GEAR on so he can retrieve you. Obviously the same goes with scuba, although IMO, with scuba you should be completely self reliant because it's all too common for your buddy to be doing his/her own thing or if your spearfishing for example they are likely more consumed with their hunt rather than watching you.