As chuck stated, get everything in writing/times stamped and signed or his refusal to do so. Ta
take videos of the pool chipping out process and see the sizes that come out...grab some of the bigger pieces and take them to your concrete driveway. Have eyewear [PPE] and let your husband hit them w a hammer. If they crumble vs barely cracking or only sm pieces chip, then you validated the shell is bad...
Viewing another gunite shell is a good idea, ones that cured. However, not sure how the PB is going to let you take a hammer to it. If there is any left over gunite, take a few pieces of that and try the same hammer method as described above.
After validating the pool shell is bad, it's time to have a one-on-one will PB and show him your videos and evidence. He will draw the same conclusion as you and if not, then have husband pull out the big guns, yet as politically correct as possible.
good luck guys,
tstex