Mhlanga was speaking to Stephen Grootes on Talk Radio 702 on Monday morning. According to Mhlanga, the incident led to three boys coming to school with hand-painted T-shirts with the message, "EFF‚ our last hope of getting our land back".
"The matter is connected to that previous case [which] was not adequately dealt [with]," he said.
The white student was given two weeks' community services as punishment for his utterances.
"That is exactly the problem and that is why these learners were aggrieved by that incident... they were not satisfied... and they felt they would use their last day to express themselves in the way that they did," he said.
Maritzburg College charged the three matriculants with acting in violation the Schools Act, but the charges have since been dropped.
Mhlanga said that the school's timing was insensitive and that there had been no consideration for the pupils.
"They are writing exams and that is our major concern. The school did not think about protecting the interests of the learners... by not subjecting them to mental stress at this time," Mhlanga said.
"The school did not think about protecting the interests of the learners, by not subjecting them to mental stress at this time."
According to the University of the Witwatersrand's Professor Brahm Fleish, the education department published guidelines in 1988 that outline what is appropriate behaviour for pupils and what is not.
He said while schools could draw up their own code of conduct, it "needs to be consistent with the law".
"The school's code of conduct needs to permit freedom of expression. It explicitly says that freedom of expression goes beyond simply the ability to speak, but includes things like what learners are permitted to wear," he said.
According to Fleish, as long as the boys did not use vulgar words or insult anyone, they should be allowed to wear the T-shirts.
"There is a difference between party-political campaigning and learners wearing a T-shirt [that] I think certainly falls under freedom of expression. It seems they were using the opportunity to wear the T-shirts to express their political views [and] not necessarily [to lobby] for a political party," he explained.
"There should be some form of space for learners to express their views," Fleish said.
EFF supports students
The leadership of the Economic Freedom Fighters (EFF) has fully supported the boys, with the party urging the school to drop the charges when the news broke last week.
— Julius Sello Malema (@Julius_S_Malema) October 13, 2017
The party has also released a statement expressing its "unconditional support" for the learners.
"In our democracy‚ there is no bylaw‚ rule or school code of conduct that must be inconsistent with our supreme law of the land‚ the Constitution," the party said in a statement.
"The young men have not killed anyone‚ stolen anything or caused any physical harm. They have simply expressed an idea and by suppressing them‚ the school is not only anti-intellectual, but also scared of the truth," the party said.