What is the importance of Safe Search as an SEO factor?
Safe Search is also an important Google factor. When the safe search mode is on, Google would filter the websites that uses abusive or cursive words. Such sites wont appear in the search results.
Consider for example, a website ABC appears in the first page of the SERP for a keyword XXXX in third position when safe search mode is OFF.
When safe search mode is ON, some other site XYZ appears to be in the third page of SERP and ABC is not even in the 10th position of the SERP. This is because, ABC has used some abuse content or it is not safe to work. Hence, it is not being listed in the SERP results page.