If you restrain someone who was 'trying to get into a toilet', what happens when that person is denied access to the toilet?
Is there inevitably a mess in the cabin?
Does their 'need' to use the toilet go away, or do you permit them to enter the toilet and risk them refusing to come out?
I realise that cabin crew will have the means of unlocking a toilet door, but if the occupant is determined to prevent the door being opened, what then?
I suppose the miscreant is safely detained . . .