There are at least three headlines for this article on the ABC News front page. I chose one that wasn't offered by Lemmy when I posted this.

In 2019, Mr Nugent replied to Ms Haines directly on the platform and appeared to compliment her, describing her as a "politician who takes climate change seriously".

Since that first interaction, he posted four other replies mentioning her on X, with the most recent being in 2021.
None indicate any anger or malice towards the independent MP.

He does not appear to show consistent support for any political party and has been critical of the major parties at state and federal level.
In recent years, he has posted on X in support of Gaza, posting fundraisers and being critical of Israel.

The West Australian has gone all-in on the "Anti Israel" angle. I guess they only went back the last couple of years. They certainly didn't mention his playing in the High School footy team. According to The West, he's super mega hateful toward Israel and this is all about Gaza. Front page, and a Page 3-4 spread.

Yesterday, all the newsheads were reporting that the family were friends with Helen Haines.

In the statement, Mr Nugent's father Rod Nugent and Rod's partner Christine Cunningham said Ms Haines had been their friend for more than 20 years and Monday's events were "devastating and unfathomable".

"Helen Haines is a deeply respected, valued and much loved member of our local community," the statement said.

Also from the bits and pieces released so far, it appears he was just driving by. He saw Helen in the street and let the dark thoughts through. There doesn't appear to be a master plan behind his actions - no 'what next?' or 'what will this achieve?' or anything. I'm not sure we're going to get a coherent reason why he did this or what he was trying to achieve.