Turns out my nfs options were working and behaving properly. I was expecting the wrong error code in Apache. I was expecting 500 whereas Apache was returning 404's. Here are the nfs mount options I am using: ro,soft,timeo=1,retrans=0,udp,intr,noac
I used iptables to drop all outgoing packets destine to my NFS server and Apache began responding (rather quickly) with 404's.