If you're sure your dad is going to dive one way or the other I would recommend finding exactly what the problem is, minimize the risks and enjoy your dives with him, knowing that he will be diving as safely as possible when he is with you.
Of course there are risks to this. He may die a horrible, tramatic death while you are diving with him and you need to try to analyze what effect this may have on you. Will you be able to tell yourself that you were there and did everything possible to help and that he died doing something he loved? Or will you spend the rest of your life second guessing yourself? Thinking you should have stopped him somehow or that you could have saved him if only...?
But there are also risks with not diving with him. He could start solo diving where there is no chance of rescue if something happened. Or he could live to 100, diving the entire time, and die of a non dive related cause and then you run the risking of spending the rest of your life asking yourself why you missed out on all those dives.
Of course there are risks to this. He may die a horrible, tramatic death while you are diving with him and you need to try to analyze what effect this may have on you. Will you be able to tell yourself that you were there and did everything possible to help and that he died doing something he loved? Or will you spend the rest of your life second guessing yourself? Thinking you should have stopped him somehow or that you could have saved him if only...?
But there are also risks with not diving with him. He could start solo diving where there is no chance of rescue if something happened. Or he could live to 100, diving the entire time, and die of a non dive related cause and then you run the risking of spending the rest of your life asking yourself why you missed out on all those dives.