I do not need to know all of those details in order to provide a general response to a general question. The types of details you are asking for would be appropriate if you were representing this client and advising him as part of your fiduciary duties. However, none of that is needed here because: a) none of us represent Mike, b) none of us have represented ourselves as attorneys, and c) none of us owe fiduciary duties to Mike. This is a general forum where we exchange ideas and opinions. My answer is based on the details provided, not on what has not been provided.
With regard to "interfering with an agency relationship", Mike solicited for an answer to his question. Answering his question is not "interfering with an agency relationship" when the question was posed in a public forum by the seller. Hypothetically, if I had called the seller and said "hey, your agent sucks and you should use someone more experienced" then yes, that would be interfering with an agency relationship. But since I didn't do that, I don't see how this is even relevant to our discussion. For goodness sake, we don't even know if Mike has an agent!
Agents arguing amongst each other is not a violation of NAR's code of ethics. If I don't agree with something an agent says, I'm free to express that disagreement. Soliciting that agent's clients or interfering with that agent's represented relationships is a violation of NAR's code of ethics. Saying that I disagree with Randy, Debbie, Dominique, etc. is in no way disparaging anyone. Why does disagreement=disparagement? Have we lost our ability to have a healthy debate? I haven't.
We live in an overly litigious environment and as agents we are taught from day 1 to be mortally afraid of liability of any sort. Hence the types of responses to Mike's simple question. I like to bring more value to the equation by sharing my opinion rather than offering a textbook answer that will limit my liability. If the latter is all we have to offer, then why are we all here? Certainly it has more to do with being helpful to consumers than generating business for ourselves, right?