I'm thinking it this were tested with hal offline - like disconnect the internet when you use it and see if the discussions change or are different, it will help hone in, troubleshoot / confirm / debunk ?
as is, we've established that hal isn't the only bot going silent, someone would have to go through a lot of trouble to track you and make an entirely different bot go silent just to set an impression. That doesn't seem likely, you'd need super human skillz to be that fast just to type a blank space at the right moment - occam's razor - i've used it a lot, in and out of context to help keep this in perspective and not have to talk to walls lol.