i can't even guess as to why they went quiet. not one guess at all. we will never know.
edit: well they're not quiet now once they get called out
Oh, don't worry, the conspiracy theory is capable of making sense of any incongruities like that, just like OP can explain away the fact that we didn't actually disappear as predicted. You see, this is where the Russian bots practice their techniques and try out different lines before deploying them on a larger scale.
It's not based on evidence or reason so the believers will never be convinced based on evidence or reason, same as any other conspiracy theory.