The boy's mother said while going forward with her story had been extremely stressful, she felt it was the only way to ensure other parents at the school would get the truth about what had happened.
"It was incredibly difficult because I was aware of the impact on other children in the school but I felt it was important. I thought parents had the right to know, had the right to transparency," she said.
"I knew when I made the complaint that while the school stopped using the room for my child, they were still using it for other children. I felt that was inappropriate, and that cemented my choice to go to the media. It hadn't been my intention at the start."
The mum, who didn't want to be identified to protect her son - who is now at a new school, said her family had been hurt by the school's actions because they had worked very hard to support teachers with his sometimes challenging behaviour.
"As a family we went above and beyond to ensure he was learning to the best of his ability. We used best-practice therapists and paid for a teacher aide, yet behind our back the school went and locked him in a room anyway," she said.
"It's not appropriate. Staff need better training. Yes, he's challenging but he's also beautiful and amazing and he deserves to be treated like a human being."
The mum said she would take her other children out of the school at the end of the year as she felt the principal and board had not been accountable.
Another mum from the school, Ngaire Mansfield, whose 6-year-old son Baxter had also been placed in the room, said she felt the legislative change was "a step in the right direction".
"It should be a catalyst for further change. It's united a lot of people who were hitting a wall with the due process. It hasn't been working, and the media spotlight has shown that," she said.
Mansfield said she thought the family who took the story public were "so brave" and deserved support, which was why she and her husband Jeremy chose to speak out.
"Baxter was already at a new school so we were able to speak freely. I'm so glad it was worth it," she said.
However, she too felt the principal at Miramar Central and the board were not accountable - and she was still angry that some parents were unaware if their children had been in the room.
"That was our reason for leaving the school. It still riles me."
Austism Action advocate Kim Hall, who supported the family through the complaints process, said the education minister had made the right call.
"The use of seclusion should have been made illegal a long time ago but it will come as a relief to families that the Government are finally listening," she said.
The education minister will invite the Education and Science committee to add a supplementary order to its update of the Education Act.
She said while she expected there would be hearings, there was nothing to presuppose that the new law would not pass.
"While once this practice was accepted in the 80s and 90s, it no longer is," she said.
Not only were there "significant physical and psychological risks" in placing a child alone in a room, and it also presented serious health and safety risks in the event of an emergency such as a fire, she said.
Seclusion is defined as the practice of a student being involuntarily placed alone in a room at any time or for any duration, from which they cannot freely exit or believe they cannot freely exit.
Schools will still be able to use "time out" rooms, where a student voluntarily takes themselves to an agreed space or unlocked room, like a sensory room, to calm down; or when a teacher prompts a disruptive student to work in another space, as the ministry recognised the need to keep everyone safe.
An Ombudsman investigation into the use of seclusion rooms is ongoing.
