Why did they ever commit to this advertising in the first place?
I do not know.
Usually, advertising is something that is bought in blocks. They were most likely not shown any of the promos that we got to see and when they were alerted that their package deal included the time slot for this show, combined with the promos we all saw, they called in the marketing reps for Discovery and demanded not to put their ads on this show or lose the deal altogether.