The audience was dead

1 Pe 4.6:

For this is why the gospel was preached even to those who are dead, that though judged in the flesh the way people are, they might live in the spirit the way God does. 

and 3:19-20:

He [Christ] went and proclaimed to the spirits in prison, because they formerly did not obey, when God's patience waited in the days of Noah, while the ark was being prepared…

I have preached to audiences that seemed rather dead, but nothing like this group Jesus was speaking to.

I have more questions than answers about this.