Both of you are right. They should be doing a much better job of promoting health, but trying to fat shame your way out of a pandemic isn't going to work. Fear mongering and telling 42% of American adults that they are going to die because they are fat may not be a great idea.
A lot of the underlying conditions that kill people with corona are also correlated with obesity - it's not the obesity in and of itself that is likely the main problem. So doing a campaign based just on a simplistic BMI could have bad mental health impacts. There are people in the obese BMI category who are otherwise relatively healthy and at low-risk, so it's not a great overall health strategy to scare these people. You would have to be careful about the messaging.
Also, Bill Maher has always had an anti-fatty shtick, so he is just scraping that barrel again. It doesn't mean he is wrong, but the dude is a senior citizen celebrity who probably has body dysmorphia and projects some of that self-hate on to fatties.