Hillside - I don't condone solo diving, but he could easily dive spots where the crew snorkels. Indians is a great example of this. the Chimney is as well.

Zanshin, I'm not saying people don't do it. I just know most I dive with wouldn't. And I wouldn't allow it on my trip. All other reasons aside, if they do have an issue, that would certainly make it miserable for the rest of the crew. Certainly there are things you can do to minimize the risk when diving solo though... There's already enough risks though that personally, I wouldn't add in any others.