The split and subsequent reunion has been a key talking point since the start of the year, particularly as Kostecki was meant to start the season as the reigning champion.
His return has been widely welcomed by his driver colleagues, Walkinshaw Andretti United star Mostert the latest to explain why having the champion on the grid is important for the category.
According to Mostert having a driver like Kostecki in the field is a reason for the rest of the teams and drivers to “step up to another level”, a benefit for the series as a whole.
“It’s always good when the reigning champion is on the grid,” said Mostert after topping Practice 1 today.
“We just hope he’s happy and he’s come back in a good frame [of mind]. You talk to him a little bit in the paddock and he seems in good spirits, he’s ready to go racing.
“No doubt he’s probably spoken to a few of us, ready to bash into a few of our doors, which is good to see.
“Hopefully we get to see him out there and race against him and hopefully he can find his feet as quick as he can because it makes everyone else lift in the championship too, like what Gizzy did for us for a lot of years, and when McLaughlin was here.
“All of those guys make every other team and every other driver step up to another level, and Brodie is that type of driver. It’s exciting to have him back.”
Kostecki has so far made one TV appearance on the broadcast during which no details of the Erebus saga were discussed.
The current indication is that his only media for the weekend will be unavoidable TV requirements and any category-mandated press conferences should he finish in the top three.
He was 12th fastest in the sole practice session earlier today.