I weigh about 145 and I am in a size 6 jeans. I can wear a size 8 but they are a little loose. At 155 I was in size 8. So conceivable, depending on the brand of jeans, the person *could* be wearing a size 10 at 179 lbs.
Vanity sizing is surely here to stay. When I was smaller and in my 20s, my regular pants size was between an 8 and 10. As I have gotten older and larger, it has decreased!