The pair engaged in a heated battle for victory in today's opening sprint race in Perth, spending the last few laps swapping paint.
Kostecki was leading for much of the battle, the Erebus driver defending hard as he tried to keep a clearly faster van Gisbergen at bay.
He was eventually shown the bad sportsmanship flag for blocking, shortly after which van Gisbergen was able to execute a race-winning pass at turn 6.
Immediately following the race Erebus boss Barry Ryan criticised race control for its attempts to temper Kostecki's defence.
"If they want good racing, that's good racing," he told the broadcast.
"There was only three laps to go. You can technically block with three laps to go, and that's all he did. If it was 10 laps to go, Brodie would have been smart enough to consolidate second. But he's racing for the win.
"We're not racing for 10th, we're racing for the win. Everyone puts up the white flag when Shane comes, but Brodie doesn't. We proved that today and we'll prove it again in the future. And beat him next time.
"Shane is cheeky, tries to hit him under brakes so he can't get on the throttle. Brodie knows all that stuff and Brodie hit the brakes to back him up. That's racing. That's what we want. When Shane drives up to the back of people, and passes them because they roll out the white flag, you don't want that. That's crap."
Both drivers were perplexed with the situation, van Gisbergen explaining that he felt Kostecki had done nothing wrong.
However he said that if there is leniency on blocking, there should also be leniency on rear bumper contact when trying to get past another car.
"Obviously [it was] on edge of what’s legal and what’s not; I love that stuff but obviously it’s a fine line with what’s allowed in our rules," he said.
"Like he got a bad sportsmanship flag and I’m not allowed to bump him out of the way, so it’s a fine line. I loved it but it’s obviously always a grey area in our rules.
"A one-on-one battle, you should be able to do what you want – but I don’t know.
“You want to be able to defend your position. He was doing nothing wrong with his defending. He was propping me up a bit but yeah, there should be some leeway for me to do it in the opposite way, I feel."
Kostecki added: “The last time I think I remember doing something like that was probably go-karts, so it was a long time ago.
"Like Shane said it was a lot of fun, obviously not as fun for me coming second, but had a lot of fun during the time on track racing him. It is for the win and it was three laps to go so it’s how races should go
“I was pretty confused by [the bad sportsmanship flag] afterwards. We’ll have to go through it and see what’s allowed and what’s not. Like Shane said, it’s pretty confusing."
