Reading between the lines from the text here (which I admit is speculation), I think there's substantial chance the admissions office feels there may be a shoe yet to drop (note that her son's body was never found... which based on the text of the article is likely to mean she never told the authorities where it was, which raises questions about what else might have happened).

They specifically cite the possibility that her description of her crime amounted to deception. Between that and the possibility of more secret land mines that might reveal she has done something even worse (i.e. actively killed the child), I think it's totally reasonable for the administration to say "No thanks, we're full to the gills with no-risk applicants."

No one is entitled to be selected for graduate study at Harvard. And she seems to be doing fine with other offers. So I think as a society we've done reasonably well in giving her a chance at a new life.