That's a tough call. I'm assuming that we are talking about an elderly relative here. It's hard to give up something you've done all your life especially when it will likely be perceived as being more more step on the way to the grave.
However, you would not be doing the person a favor by not mentioning your concerns. If you do address the issue you may initially want to do it in a one-on-one manner, if only to spare them some embarrassment. At the very least it sounds like he, or she, needs a "range buddy" if they want to continue shooting.
Best of luck.
John