As so often happens, this brief report is too confusing for anyone to draw any reliable conclusions. History suggests it may be all we ever know.
The story says he ran out of air (as usual, it says "oxygen"), but it also says he was diving with a group, and it took a search to find the body. If he was with a group, you would expect someone to share air, and you would expect them to have a good idea of the location of the body.
In a surprisingly large percentage of fatalities, the diver is somehow separated from a buddy or team and is later found dead, with the cause of death unclear. In such cases, the air may run out because the regulator free flowed after leaving the diver's mouth. Or he might have run out of air. From this article, all we know is that a search found a deceased diver with a presumably empty tank.