He is not the one who invited him. I do not know when the invitation was offered, accepted, and announced, but I didn’t know about it until a couple of days ago. You’re right, though, that there was lack of aforethought in inviting someone controversial.
I dont know this for sure and I have no evidance for this, But I am sure a list of possible speaker was thought about 6 mnonth or more ago. You dont plan a major event like this on the fly, You plan it properly. You also have to see if speakers can even attend or if they want to attend (IE many Charedi Rabbis wont leave E’Y” for any reason)
If a possible list of speakers was drawn up, and If the Vizitzher Rebbe wanted to see this list, I am sure if he asked, they would have let him see it. He could have known (Or maybe he even DID know) Months ago about the speakers.