I guess it depends on the time the kids were left in the car. 7 am? Temp 60 degrees not a problem.
12 noon 86 degrees, problem.
Also, how Situated?
Did he deliberately try to park them in a shady area? I can’t really tell what is meant by “back” of the lot in that location, but there are some trees near some edges and the building can shade early or late on one side.
But the whole “back of the lot” makes me think maybe he wanted to hide the fact he didn’t want to remove the kids.