Calling it a "moral panic" feels almost offensively wrong to me.
McDonald's is very legitimately a serious problem in America today. Obesity and related conditions- Type 2 diabetes, high blood pressure, etc are at mind boggling epidemic levels. Americans today are living shorter, sicker lives than their parents despite tremendous improvements in medicine, working safety, automobile safety and less smoking almost entirely due to obesity related conditions. Childhood obesity is setting millions of children down a path of suffering before they're old enough to understand that they're being harmed or having the agency and autonomy to correct it.
This isn't a "moral panic" over something harmless like kids playing dungeons and dragons or listening to rock and roll, this is arguably the largest health and wellbeing concern in America today. If anything, as a society we probably have too much moral panic about stigmatized things like opioids and guns that impact a pretty small percent of people and have not enough concern about the unfortunately normalized things like 3/4ths of people being overweight and 4/10 being obese.