Both it seems are scared of being ambushed by activist's from the other side.
The result is now talk that there will not be questions from the floor to the Leaders at all, and that, presumably, questions will be submitted in advance on papers and the presenter will decide. There's also concern about clapping, presumably in that if the audience is loaded one way or another it will clap louder for one leader than another and thus push the view that their response is more popular.
All valid concerns I guess, but isn't it rather sad that the two men who would be Prime Minister are arguing about how they want the audience to be loaded in their favour anyway? It's like two football teams arguing that their goalposts should be smaller than they're opponents.
Surely the best approach is to simply have a lottery for the audience. Don't give any allocation of tickets to any particular party, and have some sort of independent verification that the drawing of names for tickets is done randomly, then let the leaders take their chances.
Of course, political activists will want to go and have their moment where they can say something clever and sharp, but the truth is that they're all in the minority in the country anyway.
This argument tells us more about the low esteem in which the normal non-politically active majority are held than anything else.