The above post and many others like it is a fair reason, don't you think?
No need to ask again.
I think phrases like "I've done my own experiments" then refuse to say what they are, can be perceived by others as being untruthful. It hints to a complete absence of any experiments. It is fair enough to doubt the results and validity of experiments made over thousands of years of scientific development. But when they are replaced by "secret" experiments it doesn't add much balance.
It is along similar lines of "well I think I have a greater information source", which is a standard line from a conspiracy theorist play book. A lad in my team is like a work conspiracy theorist, and follows the same patterns as flat earth, twin towers attacks and other discussions I've seen. He comes out will all sorts of stuff that is apparently going on and going to happen at work, and each time challenged "well I have my information sources, but I can't tell you what they are".
One day he was claiming something, getting the rest of the team wound up and I had to say that is the opposite of what is happening. Sure enough "Well, I think I have a better source of information than you on this one". "Erm no. The decision on this was made half an hour ago between me, the director and other senior managers. I was the one who put forward this solution". The response, a knowing smile and a nod, "as long as you feel like you have been involved, that is the main thing but I know for certain that is not what is going to happen.". Sure enough what I said happened and what he claimed didn't. But he was convinced he knew better. Could not reveal his information or sources of course.
When it comes to conspiracy theorists, I think that is a natural form of defence. You doubt some of the maths I use as bowing to authority, fair enough. But, I maintain things like the circumference of a circle is 2πr. I have something out there to be attacked along with all the other maths and physics posted on this forum. But what I find with conspiracy theorists is they never have the details, never the experiments, only ever vague hints. Nobody is going to come out and say the circumference is 14cos(squirrel), because it can be disproven. Or in other words, nothing there to be attacked. It is a safe defence. I think it is what keeps their discussion going. Something with details can be shot down, a vague hint can't, so their theory continues. There is also the attention grabbing bit "Oh please tell me more of your wisdom?", which both gives attention and elevates their status in their minds as a sage holding secret wisdom, rather than what they actually are.
The discussion here today is a great example. "I have experiments to prove what I'm saying", "Can you tell us more", "No"...oh, well that is the end of that discussion isn't it? I think it is the same reason you will not provide the shape of your earth. We can demonstrate the globe works, but can't prove or disprove yours, because there is nothing there to attack or disprove. It is the invisible rhino in the corner that only you know is there.