Without more information, it's impossible to understand, or discuss what happened.
Speculating that the man was diving alone is just that, speculation. Since there are only a few outfits that are allowed to take divers on this site, I'm betting that a buddy or team system was in place, and there is a lot more to the story.
Suggesting that Technical divers generally don't use a buddy, team, or support system is simply not true. I'm not tech certified, but I certainly know and dive with a lot of those who are. I don't know of any tech diver who does deep dives solo. I've certainly read about them, and they exist. Such a generalization about how MOST tech divers dive however is false.
My thoughts go out to the family and friends, and maybe this discussion will become fruitful if more facts are revealed.