Conway, Kamui Kobayashi and Jose Maria Lopez went into Saturday’s decider with a 16-point deficit in the championship standings, but any hope they had of beating the sister Toyota to the title was wrecked when Bamber locked up and hit the right-rear section of the #7 GR010 Hybrid at Turn 1.
The contact dropped Conway dropped all the way down to 11th and allowed the #8 car shared by Buemi, Brendon Hartley and Ryo Hirakawa to take an easy win and with it the 2023 Hypercar title.
Toyota technical director Pascal Vasselon was unimpressed by Bamber’s driving at the start and felt he could have taken out both of the Japanese manufacturer’s car from the race.
He said: “Incredible. When you see a Cadillac locking tyres for 100 metres, you wonder where you are. Is it club racing? It's absolutely unprofessional.
“We've seen it coming. It was 100 metres before and he has... fortunately, our car resumed. But it could have been the end of the race. So here we have no words.
“It happened in Fuji. Our two cars have been pushed out of the track. And here is the same. It's absolutely unprofessional.“
He added: “It's sad that these kind of things happen at that level. It's really sad. You can have locking wheels the last five metres, yes, but a hundred metres… it's amazing.
“I could do that if I was [in the car].”
Vasselon felt WEC should impose stricter penalties to deter drivers from being aggressive at the start, having believed the two Toyotas were also hard done by in the previous round at Fuji.
“In Fuji all drivers behind us locked up,” he said. “[Laurens] Vanthoor behind us missed the apex. Both Ferrari pushed one car out. We have been lucky again with car #8 that we did not get any puncture, but Porsche #5 got a puncture.
“Because Fuji and here - same problem. So at some point we just need hard penalties for drivers doing this kind of thing.“
On his part, two-time Le Mans 24 Hours winner Bamber explained he wasn’t trying to make a pass for second, but felt sorry for impacting the title chances of the #7 crew.
Conway, Lopez and Kobayashi were able to recover to second by the start of the third hour after surviving the incident, but by then the #8 Toyota was already half a minute out in front.
“I was just going in,” he told Autosport. “I was quite happy with my position where I was and then I was braking in the middle of the brake zone.
“All of a sudden both front wheels locked which is really odd. And then to be honest I released the brakes and I tried to avoid both Toyotas, I didn't wanna hit them.
“Nearly avoided both of them, but just took the #7. So it's a real shame to affect their race. Just, honestly, a very, very light touch and we just spun the #7.
“But yeah, it's always crap to get a penalty about that. I feel more bad to be affecting those guys' races.”
Cadillac had looked strong in practice for the 8 Hours of Bahrain, with its drivers suggesting that the American manufacturer could emerge as Toyota’s closest challenger in the race.
But the #2 Chip Ganassi-run V-Series.R wasn’t as competitive in race trim as many had expected, after a 60-second stop/go penalty dropped the car a lap off the lead.
“We had high hopes after Alex [Lynn] did a great job in qualifying and the car was really good in practice,” said Bamber’s team-mate Richard Westbrook.
“It would have been nice to close out the season on a high. We were really confident going into the race, but it wasn’t to be. We’ll take this one as a learning opportunity and come back stronger in 2024.”
