Here is a possibility that no-one here has considered yet: If someone was working on a covert operation, they might have fake identity or maybe nothing to identify them, in case they were intercepted and the operation went wrong. Or the operator (or someone else) may arrange things to look as though they were an "illegal immigrant", with all identifying labels removed. This man is described as young and physically fit. Maybe he was working on something that went wrong. Maybe he was left for dead in the sea or left to appear like a suicide or attempted suicide. His training may have been to reveal nothing, however traumatized.

Under these circumstances, anyone who recognizes him is not likely to come forward to identify him - at least not publicly. The public may never be told the full story. Maybe it is already known who he is and there is a waiting game going on for someone to reveal themselves by claiming him.

Just a possibility, you understand. Whatever the truth, I say "poor young man."