Mike(new guy) left the warm up plugs in the throttle bodies when he put new plugs in. Just like carb guys hang them in the boosters, we generally lay them in the bodies. He just forgot about them and since you don't have to crack the throttle on an EFI car, it didn't show until he decked it in the burnout
Why would you do this? I've been an auto mechanic for 42 years and I wouldn't even think of setting anything in a carb or throttle body that could even remotely end up in the intake. It's just tempting fate. Everyone makes mistakes, why would you want to increase your odds of catastrophic failure?
You look at the plugs every pass on a nitrous car. We and most others have always just stuck the plugs in the carb boosters. It keeps them in order and where they can be seen. You look at the plugs with your light or scope and then put them back in the motor. Just the way most choose to do it. So when we switched to EFI our process didn't change. On our throttle bodies, they are shorter and the threads of the plugs stick out the top and are easily seen. Guess James' throttle bodies are deeper and they were overlooked.
Because YOU wouldn't do it doesn't matter. You likely do things I would never do, so none of that matters. A mistake was made, it cost him and is likely a mistake he will never make again
