"Neither he is" &c used here in UK likewise, just as Joybell describes.

"Rhubarb" here is thought of as the word actors say over and over to give impression of background chat going on behind the main action/dialogue. Could the usage Q describes two or three posts back derive from this, in the sense of a loud hubbub in which the individual words are not all identifiable? [Note also similarity of words 'hubbub' & 'rhubarb', at that.]

~Michael~