The main character is not an old man. He is a young man, who, while in a coma, had his body grow old. This is a major part of the drama that takes place. Can you imagine what he must be feeling? Leave it to Masamune Shirow to come up with such a premise. Near the last few episodes, the characters become really amazing. More so than other Shirow works, this one is about love. Love between friends, family, the possibilities of love or lust in an age when everyone and everything is connected.
The whole thing about him being an old man is just one of the unusual things about this anime, mind you, stranger things happen in some of the eps.