Sometimes a person, if they can't deal with their own private thoughts, will try to let go of them through avoiding them, getting their attention to something else. But if a person can't deal with that, perhaps it's not for us to say that that is not a good technique for someone who doesn't know how to deal with these thoughts. Perhaps that person can then not actually dwell in the negative ones.
It's important for us to not have an idea of how we want other people to deal with their sicknesses and death, because this can create a lot of suffering for us. Everybody deals with it in their own way, some will seek to use it in a useful way, and others may not. We have to have a certain amount of equanimity when wanting to help others.
When my aunt was dying of cancer, I had a fairly close relationship with her so I was able to write her a letter which helped her a lot. Giving advice depends on whether you're close to the person or not. I basically didn't tell her what to do, but I told her how much I appreciated all her generous actions towards me during my life, and what wonderful qualities she manifested and how wonderful it was that she was my aunt. This made her feel very happy, because she was thinking, "Oh well, my qualities have been noticed and appreciated." So, reminding them of their positive qualities is very helpful and comforting.
It also is very Buddhist in a way to get people to reflect on their good qualities, and what they've done that's good in their life. If you're able to get them to consider what good that they've done, if they're able to receive it, it's very good. She was actually only given two months to live but she lived another year and a half, because then she decided to just live each day. So, if you know this person and the good that he has done, to remind him of those good things, it keeps their thoughts away from the negative, this is very helpful.