The "community of inquiry" framework examines the interplay between four kinds of presence (teaching, cognitive, social, and learner) to promote effective learning in online education. This paper investigates the impact of "instructor participation" ("IP"), a key component of "teaching presence," on student discourse in discussion boards with automated grading. A content analysis of 1146 contributions on the Yellowdig discussion platform suggests that high IP enhances cognitive, social, and learner presence, but remains insufficient to deter the use of AI tools, such as ChatGPT. Overall, high IP adds considerable value by modeling desirable behaviors, encouraging effort, and promoting more thoughtful online student discourse.