The woman who made the study was an assistant science professor at a community college. Publishing helps academic careers, and sensational titles help get papers published.
Her paper says, "The Bacillus species are ubiquitous and could have had numerous sources, including airborne spores..." ..."the likelihood [of the microbes' causing infectious diseases] was not determined in this study. An extensive search of the literature yielded no reported outbreaks or illnesses attributed to lemon slices in beverages."
She concluded by saying her study used water and soda, and she would really like to investigate possible contamination of olives, limes, celery, and cherries in alcoholic beverages. I hope she doesn't get a DUI while advancing scientific knowledge.