The joke is that not taking into account all known correlated predictors when performing a statistical analysis can produce absurd results. In this case, age is

The joke is that not taking into account all known correlated predictors when performing a statistical analysis can produce absurd results. In this case, age is a metric variable known to be a correlated predictor of what movies an individual has seen, the probability of their death due to COVID-19, and the probability of their being vaccinated against COVID-19. The precise relationship between those four items is beside the point here -- the point is just that if you did not take into account that age is a metric variable and that it is a correlated predictor of both vaccination status and death, then you did your analysis incorrectly.