Slade ran into the tyre barriers on the field's first run through the front chicane in Race 25 after he and Kostecki had arrived side-by-side at Turn 1.
A bump from Car #99 put the #23 PremiAir Racing into the wall, but the Erebus Motorsport driver would not be found to have committed any wrongdoing.
Click here to have your say on the state of Australian motorsport and go into the draw to win a Kincrome Tool Armour Workshop valued at $11,999.
“On the available broadcast vision that was reviewed, neither Driver was wholly or predominately to blame for the Incident.”
With that incident not referred to stewards by the Deputy Race Director and Driving Standards Advisor Craig Baird, Kostecki would go on to finish fifth.
He now leads the championship by a reduced, 104-point margin over Race 25 runner-up Shane van Gisbergen with three races and 450 points left on offer in 2023.
Van Gisbergen was himself investigated over his move for the official race lead on Matt Payne on Lap 29, when he got a run on the #19 Mustang and completed the pass as they braked for the front chicane.
Broadcast replays showed the Triple Eight Race Engineering driver climbing over the kerb through the final corner before making contact with the Grove Racing entry as they started the drag down the Gold Coast Highway.
On that, stewards advised, “No breach of the Rules was established upon reviewing the available broadcast vision.”
Tickford Racing's Thomas Randle was not referred to stewards over his Lap 1 shortcut of the front chicane after side-to-side contact with van Gisbergen, and nor did Matt Stone Racing's Cameron Hill have a case to answer when he made contact which caused PremiAir's James Golding to Spin at the Hairpin on Lap 68.
In fact, the only penalties issued were for an accumulation of tracks limits breaches or failure to give way by the 150m board at the Beach Chicane.
The chief beneficiary was Team 18's Scott Pye, who took the chequered flag in eighth position but was officially classified sixth after Brad Jones Racing's Andre Heimgartner and Walkinshaw Andretti United's Chaz Mostert each had five seconds added to their race times for track limits breaches.