Ultimately, I think you do more good by making information available (not spamming it into every thread on a forum) and then stepping back, showing some respect for the people you want to protect, and letting them figure it out for themselves.
I would like to think this would be true but the reality (IMO), from my understanding of forums, is that newcomers only read the most recent posts and don't really take the time to read through.
They get the impression from the surface; hence all the repeat posts on the same topics "I like the idea/philosophy/etc of aikido but will it work in street/octagon/space?" etc.
There is no easy solution, but I think not saying anything runs the risk of allowing the signal to noise ratio to creep in the wrong direction until finally no one can see the woods for the trees.
I don't see an effective solution; other than just not caring about anyone else's views, including all the people who may be forming them as opposed to holding on to them which doesn't appeal greatly either.