OK guys, something else has changed. Now this IS the first time I've compiled on the VPS, but I saw no errors. Eliminating wackou's tools I invoked directly and got the same error:
/home/admin/.BitShares2_bin/witness_node --rpc-endpoint "127.0.0.1:8090" --genesis-json ~/oct-05-testnet-genesis.json -d ~/.BitShares2 -s "104.236.51.238:2005"
I'm compiling on my dev machine to see if there is something related to that, bit it will take 30 minutes to complete and another 15 to upload the binary to the VPS. Bummer. Should have been ready to go. If I get the same result from dev machine build there's something besides the build host, b/c I use the same script to build in both cases. Actually I use wackou's build tools. It's a pretty straightforward build process, even if it's done manually.
Besides, it look like a silly "can't read the json file" error, and unless the VPS host is using an odd library should be extremely stable code. If the build was using a dynamic lib not available it would be a different error.