Were you offered a price on a flex liner by this inspector fellow?
Hairline cracks are of no consern in a liner...unless you have a sales job to bait a fish with.
Surprisingly he said it wouldn't be worth installing a liner due to the expense and how little it would be used. I feel it was probably more of a liability issue of saying it yeah it's fine to burn it then something happens.
I have an inspection port in my plate I'll take out and look up in and see if anything has changed.
I will get a pic when I get home.