As it is, we have scheduled another meeting this Sunday again after the Sunday service. And if he is serious I will invest for him but I prefer the long term but as a age man, really he needs an investment that can brings feed to his table daily and that is why he was insisting on the short term investment buy that cannot do him anything base on the volatile nature of Bitcoin.
I think he is thinking about Bitcoin investment because he wants an alternative source of income since he will be getting retired soon, and from the way he sounds from your story he needs something that generates quick income. You need to let him know what he needs right now is to get understanding about bitcoin first, and understand the movement of the market. Bitcoin is more profitable when people understand it first before going into it as investment. Since he is getting retired from his service anytime soon it is better for him to think of anything that can be a source of income than planning to make money from bitcoin. Bitcoin investment is good when it is longterm and it doesn't make sense when people try to depend on it.