So the intention there is clearly a rhetorical one, that not being the point, but that advertising has managed to manipulate people against their better judgment. In that sense, yes, they are victims.
Besides, believing that people suffering from an ill that is destroying their lives are free to choose (when reality clearly shows they aren't) is a callous remark.
Eating disorders are very complicated. Eating is such a low level activity that easily supersedes any rationalisations. That's why it's a good example of how bad advertising can be. So again OP is right in calling those people victims.