Brand safety as an idea isn't dangerous, and there's an entire sub-industry in the adTech space devoted to it. The bottom line is most companies don't want their ads showing up on sites or in close proximity to certain types of content (illegal, political, hate speech, etc.). Services from these companies are used to make sure when doing ads on the open web, your DSP doesn't inadvertently put your ads in places like that. One example: https://integralads.com/solutions/brand-safety-suitability/