commands in authorized_keys

Two guesses:

Protocol 2 public key consist of: options, key‐type, base64-encoded key, comment

I don't see the base-64 encoded key in the line in your authorized_keys file.

Identity added: /.... //removed
(/.../.ssh/shutdown_rsa) // removed 

Are you presenting more than one key? Your -vvv isn't complete You left out the important bit about which key was being offered. E.g.,

debug1: Next authentication method: publickey
debug1: Offering RSA public key: /Users/Kendall/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Server accepts key: pkalg ssh-rsa blen 279