There is selection bias (and other issues) not only in this study, but in which stories are promoted as well. E.g. this story presenting immigration positively gets to stay on the front page for some time, while a (admittedly anecdotal) story of Indian immigrants showing racist in-group preference at Intel (https://www.mercurynews.com/2019/07/19/korean-american-softw...) is flagged and killed.