On Tuesday the body ruled there had been "serious misconduct" but it was not enough to warrant a teaching ban.
The decision has been slammed by the mother of Allen's victim, saying he had got off too lightly.
"I'm not happy he can go back into the classroom. What are the chances he would do it again? Have they put anything in place?"
She said her son had continued his education in another city and the family had "moved on".
Allen was stood down from his duties at the small private school after the incident in June last year.
At the tribunal hearing, chairman Kenneth Johnston said the classroom assault only required a "telling off" with a warning.
"There has been a serious misconduct but it's not at the higher end of the scale," he said. "We don't think this case calls for anything more than that."
After being censured, Allen told the Herald on Sunday he regretted the incident and said its repercussions threatened to close the school he had worked tirelessly to build.
"It's a blemish on 19 years of hard work. I can't turn back the clock but I don't see why I should give up on something I'm passionate about," he said.
"Maoridom needs a lot of support as far as education goes so that's what we're here for."
Earlier Allen told the tribunal he carried a great deal of remorse about the violent outburst. His teenage sons had been forced to leave their Auckland home and attend school in another city and he had placed "the whole family under pressure".
He said the school had enjoyed years of sporting and cultural success and had celebrated its first medical graduate. Other former pupils had gone on to become successful in business.
But the axe was now hovering after the closure of the senior school at the end of last year. The school was struggling financially and the roll had plunged from 95 students to 33 in five months.
Nga Kakano Christian Reo Rua Kura board of trustees chairman Bernie Allen did not respond to calls for comment on the principal's return to school.