Except the numbers work out, and studies have made very very sweeping generalizations based on much smaller sample sizes of much larger demographics (for example the 1 in 5 myth comes from a study that had less than 100 respondents). This study is a dream compared to those.
Actually the sample size checks out. I love it when people see "Smol number not as big as big number, therefore sample size bad" and I am going to pull a very elitist argument here and say that people at Harvard University likely know more about polling than you do, just saying.