Did whoever wrote this study to be this stupid?

Depends on how you look at it. We've had this discussion before, but I modeled my situation in cFIREsim and found that delaying SS allows me to spend MORE in retirement. This is an important consideration for me, because I retired early. This means I'll be in my go-go years for longer than most people. For example, I just got back from two weeks in Hawaii swimming and snorkeling in the ocean almost every day. Last year, I downhill skied 27 days which is my all time season max. Having some extra cash dovetails nicely with these kinds of activities.

Of course, the thing we really need to know in order to make this decision is how long you will live. Which I don't know. But I can take a guess. I have lots of long lived ancestors. My mom is 91 and can do all the normal tasks of daily living. She can get up down out of the couch with no problems and doesn't require a cane or walker for mobility. I have no serious health problems. I've never smoked. I exercise regularly including weight bearing exercises as well as mobility and balance exercises, and I have a healthy diet that I mostly prepare myself. Based on my family history, current personal health, and lifestyle, the odds are pretty good I will live long past the SS break-even point.

To summarize, delaying means I have more money in the go-go years when I can enjoy it, and the odds are good I'll wind up with more money over all. If that makes me stupid, I'm happy to be in the stupid camp. Delighted even.