Im not Maori so I couldnt say. But I would assume, like singing a song, that it could be either sarcastic or directly disrespectful. I would assume in this case it was not sarcasm, but directly disrespectful, considering she ripped up the bill while performing the haka. Also the severity of the situation in terms of the issue she was protesting.

If I had to take a guess based on what I know about other Pacific Island cultures, a sarcastic haka is probably not a common thing. But could exist I guess