Shock jock Alan Jones and controversial commentator Mark Latham said Harper was "defying the school".
"We used to have special schools for children with behaviour problems," Latham said on the 4BC radio show. "Not standing is a behavioural problem, so kick her out."
Jones was also furious about the Brisbane student's decision.
"What on earth do you do ... other than call the parents in and say 'listen, these are the rules here, if you don't like them you do as we say or go somewhere else because we're not accommodating you".
Harper told The Courier-Mailthe line in the national anthem, "for we are young and free", disregarded Aboriginals who had lived in Australia for tens of thousands of years and only saw Australia as a country post-colonisation.
Jones was incensed by this and said that "colonisation brought the kind of tremendous wealth that all Australians now enjoy".
"The school only exists because of colonisation, what sort of fools are these?" Latham added
Despite the 4BC commentary, Harper has received a lot of support online.
"I do applaud her for considering the words of the national anthem, a lot of people just rattle it off and don't consider the meaning and I also applaud her strength of character to stand up for what she believes in," Today show host Georgie Gardner said this morning.
Meanwhile, her co-host Karl Stefanovic levelled blame at the parents.
"Her parents are obviously supporting her and I think that's the big problem here, her parents are supporting her in a way that I don't think is appropriate," Stefanovic said.
"The schools have rules, I'm exasperated by this this morning so if you don't like that as a parent, if you don't like that your child will have to stand for the anthem then go somewhere else. Schools have rules and they have to be abided by."
