Little Big Question # 6: The researcher as a “provoking intruder”: “researcher provoked data” in a “naturally occurring setting”?

(Article: Silverman, D. (2001). Naturally occurring talk (Chapter 6, pp. 159-192) in Interpreting qualitative data: Methods for analyzing talk, text and interaction. Thousand Oaks, CA: Sage Publications.) (See p. 159)

We have seen the difference between two kinds of data: “researcher provoked” and “naturally occurring”. Would a researcher be allowed to “inject” some questions/ideas/topics (for exemple, as catalysts) in a natural setting (like an online forum)? Would it be sound (or at least justifiable) from a methodological and ethical point of view?