I realize that their nutrition is sorely lacking, but if they've been heavy their whole lives and they've eaten junk food their whole lives it would be very hard to change their eating habits. There are people whom are below average weight/average weight that are unhealthy due to their eating habits, I realize this.
People that go on health kicks always figure they need to eat 100% clean foods and that is what sets them up for failure. The all or nothing mentality we carry really destroys us long-term because not very many people can eat 100% clean for the rest of their lives.
If the peanut butter this person was consuming fits into their calorie deficit/macros they have nothing to worry about in their weight loss journey. You don't need to eat under 15g of fat to lose weight.
Life is all about moderation.