I think the goal is to try to emotionally manipulate overweight people into exercising, by telling them that they have the "right" to exercise and be fit as fat people, as though other people are trying to "take it away" or "keep it from" them. The hope seems to be that fat people will start exercising to revel in their rebellious as they work out to be fit as fat people despite the "haters" until one day they're noticeably less fat. It's a cringe strategy but it has merit, unlike the strategy of trying to shame people into feigning sexual attraction to obesity, which doesn't work at all.