I've noticed that as quick as anyone does a post in the forums , very quickly the RET trolls 
derail the thread.
Why is that?
It's not like I go to other groups of individual who have different ideas, or opinions than mine, and then troll their group to tell them they are wrong 
How about taking a more neutral tone yourself as a start? Not all who question posts supporting the idea of a flat earth are trolls; if the post is based on assumptions easily shown to be erroneous and they know from experience of everyday things that they are difficult or impossible to explain if the Earth were flat but easily explained by the Earth being a large sphere, then speaking up is not the wrong thing to do. So why should they remain silent when something they see that is obviously wrong is posted, and they can back up their position with factual data?
If you can explain an idea when challenged, then, by all means, do. If you can't, then please at least consider that your idea might be wrong.
Are you suggesting that all ideas about the shape of the Earth are equally valid? They're not. The trick is to coherently defend whatever shape you think is right if challenged.
Historically its the same thing. RET trolls will make outrages claims themselves, often present math that is flawed and downright ridicules over and over again. The actually appears to be a systematic procedure to their modus of operandi. Once you study it, and look historically at their posts, it is quite clear.
"Trolls" again. Think about it... it seems like you're complaining that anyone who disagrees with you is a troll. Might it be possible that the initial assertion is flawed and the objections have merit? Have you even considered that?
If a claim is outrageous, then dispute it, and coherently explain why you disagree. If the math is flawed, then point out - specifically - where it's flawed. That's the beauty of math - things can actually be proven there. Sometimes ideas are presented that are patently ridiculous, and they're ridiculed. Be prepared to defend what you say. Too often, someone will come here and say "I have absolute irrefutable proof the Earth is <flat, concave, whatever> because <long-debunked fanciful idea>!" Expect such to be met with scorn. Starting in a less confrontational manner would probably reduce the chance of being ridiculed.
What are they afraid of?
Nothing here. Why are you unwilling to defend your assertions?
Why must they save our wayward opinions?
Most want to point out (sometimes obvious) flaws and rookie errors so anyone who finds this site sees, if nothing else, a counterargument to an assertion that makes little sense in the real world.
Is it possible that the mandate of this site is to actually attract folks who might be inquisitive about Flat Earth Theory, and then have the trolls pounce on them as the welcome committee just to convince them the theory is absurd?
"Trolls" again. If the theory is right, then it should be able to weather criticism; real scientists go through this all the time and expect it. Maybe their "theory" really is absurd, and they're doing a favor. If someone can defend the theory, then do so.
I honestly don't think that's the idea, and there's always the "True Believers" forum. Join that if they'll let you. I read partway through it before joining and found it was a lot of threads about naval-gazing and idle speculation, and posts congratulating each other about their "insights". Pretty boring IMO, but YMMV.
It would be a really wonderful idea if the folks who favor a FET could work more together to develop experiments to further the understanding.
So develop your experiments, already. Outside criticism will help direct you to the areas that need to be conclusively tested.
Plus, the designation "Flat Earth Believer" is a bit silly.
Beliefs having nothing to do with truth.
A child may believe in Santa Clause and the Easter Bunny, but the does not make it True.
Perhaps they need to consider some identifier as " Flat Earth Theorist"
"Theory" in the technical sense has a specific meaning. "The Earth is a flat disk" doesn't satisfy that because it lacks verifiable predictions that haven't already been found not to hold true. I refrain from using the term "Flat Earth believer" here because I don't think all who argue in favor of a flat earth here really believe it is. I prefer "Flat Earth proponent".