To me, when Poster A posts about Action X, even if Poster A is merely looking for other people's experiences with performing Action X, or advice on how to get the most enjoyment out of Action X, it's legit for Poster B to post an opinion about the rightness or wrongness of engaging in Action X. I have, for example, expressed the strident view that there should be no tickling whatsoever in a moving vehicle, especially involving the driver, because when you're in a moving vehicle, safety needs to be the priority.
I happen to agree with your philosophy of safety while driving. Normally I would regard safety measures as being up to the individual. For example, I wouldn't feel comfortable telling a guy "You MUST wear a helmet if you're going to ride that Harley!" That would be me pushing my views onto him. It should be up to the individual to decide for himself how safe he wants to be, because his decision to forego the helmet only puts himself at risk, not anybody else.
However in the case of tickling the driver of the car, you're not only putting those in the car at risk, but everybody else on the road nearby as well. That changes things drastically. You're decision not only affects yourself but the general public as well. So I wouldn't have a problem with you discouraging behavior that puts the public at risk. That would not be moralistic preaching, but rather a public service.
And when it comes to when it's all right to tickle someone, I say, if you post about tickling at all, you have to brace yourself for opinions on the ethics of it. I call it expressing an opinion, but you're free to call it preaching.
Here's the difference. If you enter a thread like this and say "that's something that I personally wouldn't do because I feel it's unethical, inconsiderate, rude, whatever," that would be stating an opinion. You're not forcing your beliefs on other people, simply stating your own views on it.
But if you make blanket statements like "It's wrong to tickle somebody who doesn't know of your fetish!" you've crossed the line from expressing an opinion to moralistic preaching. It's no longer just a matter of your personal code of ethics. The wording suggests an expectation of universal compliance, and these expectations almost always come with either a subtle or in many cases not so subtle inference that anybody who doesn't follow your code of ethics is a bad person, asshole, douchebag, or insert whatever insult suits you.
Back to the topic of the thread, the invitation is still open for anybody to talk about any situation in which they've attempted to console somebody experiencing emotional trauma by tickling them, or have even thought about it.