Am hearing you, accidental drownings very common there but cannot believe he would go swimming alone and at night and temperature under 5 Celsius. He would be well aware of sharks as well. There is a strong rip near the rocks at Cosy Corner which is concerning as is close to where his mobile stopped.
It is possible he could have fell in accidentally if climbing the rock looking for a way out. It was low tide though and his track doesn't seem to reach that far, stops on the beach. Possible he put his phone down or it fell from his pocket but would think if phone was close to the rocks or left on beach would have been found. We know it wasn't in the water on Saturday as it pinged at 1.42pm. . It just seem so strange he would even be out there on an extremely cold night, dark as well no moon, not much to see at night, and climbing cliffs or rocks at night.
Not sure how the beach looks on low tide, how far the water would be. The wind was less than 2 km an hour so very still. The ocean should not have been too rough. Would be good to know if there was big swell that night or not but the wind was calm. He wasn't drunk as by the time he would have walked there the 2 or drinks he had at Cheeky's would have been walked off, if anyone gave him more alcohol there would be no reason for them not to come forward. He didn't buy anymore so am assuming he should have been reasonably level headed. I just cannot picture climbing cliffs at night, but is possible yes. Does any artificial light reach to the rocks I wonder. Though I don't believe he went swimming that rip near the rocks is a worry if he fell into it. I have attached the pics from the Byron Bay Surfers page. It looks like a very bad permanent rip there. But I really feel there is more to this. The phone ping net day doesn't add up, even if he dropped his phone the incoming tide would have killed it, it probably would be found. Leaving his hat (if it's his) doesn't add up, him being out there in a very black night and alone doesn't add up. Details of phone ping being in another area between the Pass and Wategos doesn't add up. But is possible not all information presented to the public is correct. It is possible he fell and drowned but somehow I still don't believe it.