You cannot ask participants to post in your main thread, as kind of involvement in your topic? This is main problem , and reason why all those threads are deleted. Right?
It shouldn't be allowed. You could suggest it, but not make it mandatory I believe. This wasn't properly enforced, among other things.
Mprep does a very wise move, I strongly agree with what mprep does, it is an action moderator should take.
I don't think he acted on his own.
.. to my point of view
Nobody cares about your skewed point of view.